Hi! I can't install Optifine, please help me!
I try to copy OptiFine HD U G8 in mods folder, start the game and... nothing :-( No Optifine in settings and mods. Game version is 2.8.5

For starters you would also need Optifabric, However Optifabric/Optifine is incompatible with the modpack. I would recommend using Iris and Indium instead. Iris is a GLSL (Optifine) Shaders mod and comes with Sodium, and Indium adds Fabric Rendering API to Sodium, which is required to allow Sodium to work with the pack.
https://www.curseforge.com/minecraft/mc-mods/irisshaders
https://github.com/comp500/Indium/actions/runs/923502396

Optifine/Optifabric work incorrectly with mods AE2 and Industrial Revolution, but with Iris and Sodium no bugs with these mods!
Thank you!

And another problem - no config button for shaders. Is it normal for this mod?
iris-mc1.16.5-1.1.0
sodium-fabric-mc1.16.5-0.2.0+IRIS3-rev.2c3e7cc

I have this problem too. I see that they're using shaders in the screenshots of the modpack so what gives? What's the big secret they're hiding?

Config for shaders in iris is being worked on.

I'm closing this issue because we don't really have a desire for optifine compatibility - especially when iris with sodium/indium performs a lot better and provides shader support.