java.lang.NoClassDefFoundError: net/fabricmc/mappingio/FlatMappingVisitor
at knot//me.modmuss50.optifabric.mod.IntermediaryContextTransformer.(IntermediaryContextTransformer.java:86)
at knot//me.modmuss50.optifabric.mod.OptifineSetup$2.lambda$load$9(OptifineSetup.java:324)
at knot//me.modmuss50.optifabric.mod.ContextualMappingProvider.setContextTransformer(ContextualMappingProvider.java:72)
at knot//me.modmuss50.optifabric.mod.OptifineSetup$2.load(OptifineSetup.java:324)
at knot//me.modmuss50.optifabric.shadow.tinyremapper.TinyRemapper.apply$3041763d$58bfb62c(TinyRemapper.java:7703)
at knot//me.modmuss50.optifabric.mod.OptifineSetup.remapOptifine(OptifineSetup.java:3903)
at knot//me.modmuss50.optifabric.mod.OptifineSetup.remapOptifine(OptifineSetup.java:237)
at knot//me.modmuss50.optifabric.mod.OptifineSetup.getRuntime(OptifineSetup.java:185)
at knot//me.modmuss50.optifabric.mod.OptifabricSetup.run(OptifabricSetup.java:46)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
at knot//com.chocohead.mm.Plugin.getMixins(Plugin.java:340)
at org.spongepowered.asm.mixin.transformer.PluginHandle.getMixins(PluginHandle.java:128)
at org.spongepowered.asm.mixin.transformer.MixinConfig.postInitialise(MixinConfig.java:877)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.prepareConfigs(MixinProcessor.java:568)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.select(MixinProcessor.java:462)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.checkSelect(MixinProcessor.java:438)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:290)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:234)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:422)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:323)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:534)
at java.base/java.lang.Class.forName(Class.java:513)
at net.fabricmc.loader.impl.util.DefaultLanguageAdapter.create(DefaultLanguageAdapter.java:50)
at net.fabricmc.loader.impl.entrypoint.EntrypointStorage$NewEntry.getOrCreate(EntrypointStorage.java:124)
at net.fabricmc.loader.impl.entrypoint.EntrypointContainerImpl.getEntrypoint(EntrypointContainerImpl.java:53)
at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:399)
at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:160)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:68)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
Caused by: java.lang.ClassNotFoundException: net.fabricmc.mappingio.FlatMappingVisitor
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
... 34 more

Minecraft Version?
Optifabric Version?

for me- fabricloader 0.16.10
-- mixinextras 0.4.1
- java 17
- minecraft 1.18.2
- optifabric 1.13.16
-- mm 2.3
- skinlayers3d 1.7.4
- smoothcoasters 1.18.2-v1

• OptiFine_1.18.2_HD_U_H9.jar
  [17:51:11] [main/INFO]: SpongePowered MIXIN Subsystem Version=0.8.7 Source=file:/C:/Users/Sam/AppData/Roaming/PrismLauncher/libraries/net/fabricmc/sponge-mixin/0.15.4+mixin.0.8.7/sponge-mixin-0.15.4+mixin.0.8.7.jar Service=Knot/Fabric Env=CLIENT
  [17:51:11] [main/INFO]: Compatibility level set to JAVA_16
  [17:51:11] [main/INFO]: Compatibility level set to JAVA_17
  Failed to setup optifine:
  java.lang.NoClassDefFoundError: net/fabricmc/tinyremapper/IMappingProvider
  at knot//me.modmuss50.optifabric.mod.OptifabricSetup.run(OptifabricSetup.java:46)
  at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
  at knot//com.chocohead.mm.Plugin.getMixins(Plugin.java:340)
  at org.spongepowered.asm.mixin.transformer.PluginHandle.getMixins(PluginHandle.java:128)
  at org.spongepowered.asm.mixin.transformer.MixinConfig.postInitialise(MixinConfig.java:877)
  at org.spongepowered.asm.mixin.transformer.MixinProcessor.prepareConfigs(MixinProcessor.java:568)
  at org.spongepowered.asm.mixin.transformer.MixinProcessor.select(MixinProcessor.java:462)
  at org.spongepowered.asm.mixin.transformer.MixinProcessor.checkSelect(MixinProcessor.java:438)
  at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:290)
  at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:234)
  at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202)
  at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:422)
  at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:323)
  at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218)
  at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
  at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
  at java.base/java.lang.Class.forName0(Native Method)
  at java.base/java.lang.Class.forName(Class.java:467)
  at net.fabricmc.loader.impl.util.DefaultLanguageAdapter.create(DefaultLanguageAdapter.java:50)
  at net.fabricmc.loader.impl.entrypoint.EntrypointStorage$NewEntry.getOrCreate(EntrypointStorage.java:124)
  at net.fabricmc.loader.impl.entrypoint.EntrypointContainerImpl.getEntrypoint(EntrypointContainerImpl.java:53)
  at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:399)
  at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:160)
  at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:68)
  at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
  at org.prismlauncher.launcher.impl.StandardLauncher.launch(StandardLauncher.java:100)
  at org.prismlauncher.EntryPoint.listen(EntryPoint.java:129)
  at org.prismlauncher.EntryPoint.main(EntryPoint.java:70)
  Caused by: java.lang.ClassNotFoundException: net.fabricmc.tinyremapper.IMappingProvider
  at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
  at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
  at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226)
  at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
  at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
  ... 28 more
  [17:51:12] [main/INFO]: Initializing MixinExtras via com.llamalad7.mixinextras.service.MixinExtrasServiceImpl(version=0.4.1).
  Process crashed with exitcode -1073741819. hope this helps

Support is not proved for those that use cracked launchers (Prism Launcher).