Game crashes whenever I try to view my skin. This is the report (let me know if you need more of it)
---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.

Time: 06/01/21 17:15
Description: Rendering entity in world

java.lang.NoSuchMethodError: com.mojang.blaze3d.matrix.MatrixStack$Entry.func_227870_a_()Lnet/minecraft/client/renderer/Matrix4f;
at com.unascribed.ears.EarsLayerRenderer.renderFront(EarsLayerRenderer.java:131) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.common.EarsCommon.render(EarsCommon.java:54) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.EarsLayerRenderer.render(EarsLayerRenderer.java:56) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.EarsLayerRenderer.func_225628_a_(EarsLayerRenderer.java:32) ~[?:1.1.0] {re:mixin,re:classloading}
at net.minecraft.client.renderer.entity.LivingRenderer.func_225623_a_(LivingRenderer.java:204) ~[?:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,xf:OptiFine:default,pl:mixin:APP:obfuscate.mixins.json:client.OptifineLivingRendererMixin,pl:mixin:A}
at net.minecraft.client.renderer.entity.PlayerRenderer.func_225623_a_(PlayerRenderer.java:64) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:abnormals_core.mixins.json:client.PlayerRendererMixin,pl:mixin:APP:ears.mixins.json:MixinPlayerRenderer,pl:mixin:A,pl:runtimedistcleaner:A}
at net.minecraft.client.renderer.entity.PlayerRenderer.func_225623_a_(PlayerRenderer.java:41) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:abnormals_core.mixins.json:client.PlayerRendererMixin,pl:mixin:APP:ears.mixins.json:MixinPlayerRenderer,pl:mixin:A,pl:runtimedistcleaner:A}
at net.minecraft.client.renderer.entity.EntityRendererManager.func_229084_a_(EntityRendererManager.java:310) ~[?:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,xf:OptiFine:default,pl:mixin:APP:quark.mixins.json:client.EntityRendererManagerMixin,pl:mixin:A}
at net.minecraft.client.gui.screen.inventory.InventoryScreen.func_241611_a_(SourceFile:149) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.client.gui.screen.inventory.InventoryScreen$$Lambda$15940/1453742288.run(Unknown Source) ~[?:?] {}
at com.mojang.blaze3d.systems.RenderSystem.runAsFancy(SourceFile:1439) ~[?:?] {re:mixin,re:classloading}
at net.minecraft.client.gui.screen.inventory.InventoryScreen.func_228187_a_(SourceFile:149) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.client.gui.screen.inventory.CreativeScreen.func_230450_a_(CreativeScreen.java:727) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.screen.inventory.ContainerScreen.func_230430_a_(ContainerScreen.java:88) ~[?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:mixin:APP:quark.mixins.json:client.ContainerScreenMixin,pl:mixin:A,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.DisplayEffectsScreen.func_230430_a_(DisplayEffectsScreen.java:48) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.screen.inventory.CreativeScreen.func_230430_a_(CreativeScreen.java:608) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraftforge.client.ForgeHooksClient.drawScreen(ForgeHooksClient.java:290) ~[?:?] {re:classloading}
at sun.reflect.GeneratedMethodAccessor45.invoke(Unknown Source) ~[?:?] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.optifine.reflect.Reflector.callVoid(Reflector.java:717) ~[?:?] {re:classloading}
at net.minecraft.client.renderer.GameRenderer.func_195458_a(GameRenderer.java:821) ~[?:?] {re:classloading,pl:accesstransformer:B,xf:OptiFine:default}
at net.minecraft.client.Minecraft.func_195542_b(Minecraft.java:976) [?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:607) [?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.main.Main.main(Main.java:184) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_51] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.4-35.1.29.jar:35.1] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$488/2097614581.call(Unknown Source) [forge-1.16.4-35.1.29.jar:35.1] {}
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.6.jar:?] {}

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Thread: Render thread
Stacktrace:
at com.unascribed.ears.EarsLayerRenderer.renderFront(EarsLayerRenderer.java:131) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.common.EarsCommon.render(EarsCommon.java:54) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.EarsLayerRenderer.render(EarsLayerRenderer.java:56) ~[?:1.1.0] {re:mixin,re:classloading}
at com.unascribed.ears.EarsLayerRenderer.func_225628_a_(EarsLayerRenderer.java:32) ~[?:1.1.0] {re:mixin,re:classloading}
at net.minecraft.client.renderer.entity.LivingRenderer.func_225623_a_(LivingRenderer.java:204) ~[?:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,xf:OptiFine:default,pl:mixin:APP:obfuscate.mixins.json:client.OptifineLivingRendererMixin,pl:mixin:A}
at net.minecraft.client.renderer.entity.PlayerRenderer.func_225623_a_(PlayerRenderer.java:64) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:abnormals_core.mixins.json:client.PlayerRendererMixin,pl:mixin:APP:ears.mixins.json:MixinPlayerRenderer,pl:mixin:A,pl:runtimedistcleaner:A}
at net.minecraft.client.renderer.entity.PlayerRenderer.func_225623_a_(PlayerRenderer.java:41) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:abnormals_core.mixins.json:client.PlayerRendererMixin,pl:mixin:APP:ears.mixins.json:MixinPlayerRenderer,pl:mixin:A,pl:runtimedistcleaner:A}
-- Entity being rendered --
Details:
Entity Type: minecraft:player (net.minecraft.client.entity.player.ClientPlayerEntity)
Entity ID: 431
Entity Name: DrPineapple
Entity's Exact location: 6744.50, 84.00, 12051.50
Entity's Block location: World: (6744,84,12051), Chunk: (at 8,5,3 in 421,753; contains blocks 6736,0,12048 to 6751,255,12063), Region: (13,23; contains chunks 416,736 to 447,767, blocks 6656,0,11776 to 7167,255,12287)
Entity's Momentum: 0.00, -0.08, 0.00
Entity's Passengers: []
Entity's Vehicle: ERROR NullPointerException: null

-- Renderer details --
Details:
Assigned renderer: net.minecraft.client.renderer.entity.PlayerRenderer@3dbb78a0
Location: 0.00,0.00,0.00 - World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Rotation: 0.0
Delta: 1.0
Stacktrace:
at net.minecraft.client.renderer.entity.EntityRendererManager.func_229084_a_(EntityRendererManager.java:310) ~[?:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,xf:OptiFine:default,pl:mixin:APP:quark.mixins.json:client.EntityRendererManagerMixin,pl:mixin:A}
at net.minecraft.client.gui.screen.inventory.InventoryScreen.func_241611_a_(SourceFile:149) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.client.gui.screen.inventory.InventoryScreen$$Lambda$15940/1453742288.run(Unknown Source) ~[?:?] {}
at com.mojang.blaze3d.systems.RenderSystem.runAsFancy(SourceFile:1439) ~[?:?] {re:mixin,re:classloading}
at net.minecraft.client.gui.screen.inventory.InventoryScreen.func_228187_a_(SourceFile:149) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.client.gui.screen.inventory.CreativeScreen.func_230450_a_(CreativeScreen.java:727) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.screen.inventory.ContainerScreen.func_230430_a_(ContainerScreen.java:88) ~[?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:mixin:APP:quark.mixins.json:client.ContainerScreenMixin,pl:mixin:A,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.DisplayEffectsScreen.func_230430_a_(DisplayEffectsScreen.java:48) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.client.gui.screen.inventory.CreativeScreen.func_230430_a_(CreativeScreen.java:608) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraftforge.client.ForgeHooksClient.drawScreen(ForgeHooksClient.java:290) ~[?:?] {re:classloading}
at sun.reflect.GeneratedMethodAccessor45.invoke(Unknown Source) ~[?:?] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.optifine.reflect.Reflector.callVoid(Reflector.java:717) ~[?:?] {re:classloading}

-- Screen render details --
Details:
Screen name: net.minecraft.client.gui.screen.inventory.CreativeScreen
Mouse location: Scaled: (320, 331). Absolute: (641.000000, 663.000000)
Screen size: Scaled: (479, 504). Absolute: (958, 1008). Scale factor of 2.000000

-- Affected level --
Details:
All players: 1 total; [ClientPlayerEntity['DrPineapple'/431, l='ClientLevel', x=6744.50, y=84.00, z=12051.50]]
Chunk stats: Client Chunk Cache: 1225, 841
Level dimension: minecraft:overworld
Level spawn location: World: (6749,81,12053), Chunk: (at 13,5,5 in 421,753; contains blocks 6736,0,12048 to 6751,255,12063), Region: (13,23; contains chunks 416,736 to 447,767, blocks 6656,0,11776 to 7167,255,12287)
Level time: 300 game time, 300 day time
Server brand: forge
Server type: Integrated singleplayer server
Stacktrace:
at net.minecraft.client.world.ClientWorld.func_72914_a(ClientWorld.java:617) ~[?:?] {re:mixin,re:classloading,xf:OptiFine:default,pl:mixin:APP:abnormals_core.mixins.json:client.ClientWorldMixin,pl:mixin:A}
at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2024) [?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:623) [?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.main.Main.main(Main.java:184) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_51] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.4-35.1.29.jar:35.1] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$488/2097614581.call(Unknown Source) [forge-1.16.4-35.1.29.jar:35.1] {}
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.6.jar:?] {}
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.6.jar:?] {}

Why did you close the issue?

This is weird; the "rotate" method on MatrixStack is missing...

It would be good to see the complete game log rather than just part of the crash report. Please upload that as a file or put it on Gist.

@unascribed
optifine?

...If OptiFine is deleting methods from vanilla classes then I'm just going to stop supporting it.

I'm pretty sure it does that or something similar.

I'm going to call this an OptiFine issue. Nothing I can do on my side as OptiFine is closed source, and if it is disappearifying random vanilla methods then there isn't really anything I can try to do either.