Optifine has quite a few problems. Fortunately, this pack has you covered. This pack includes all features from Optifine, but for Fabric! You can add more mods of your choosing at your leisure. Before complaining that a resource pack doesn't work please read the compatibility list below.

Current features:

Improved performance
Improved rendering and framerate
Eye-candy options
Improved lighting performance
Modded shaders
Connected grass
Capes

For resource packs:

Skybox support
More customisable light, biome, and other colours
Connected textures
Better item texture customisation (CIT)
Better block entity customisation
Better entity feature customisation
Better entity model customisation
Better GUI customisation

Tested Resource Packs

Tested Broken

Resource loading error (occurs with and without FabricSkyBoxes Interop)

Very broken. Consider using Stay True or BetterVanillaBuilding instead.

Mobs appear invisible.

Broken textures.

Partially Broken

Contains broken paths. Broken paths must be permitted.

Contains broken paths. Cow and sheep textures are broken. Consider using Better Farm Animals or Reimagined.

Broken animations.

Contains broken paths. Additionally:

Most animal models have incorrectly oriented model parts. (Pig, Cow, Chicken variants)
Zombie textures are broken.
Piglin and Piglin brute variants do not work.
Panda, parrot, pufferfish, squid, glow squid, and silverfish models not supported by CEM mod.

Reimagined, Better Farm Animals, and BetterVanillaBuilding are alternatives with similar features

DeOFed