A straight-forward article with a small piece of very important advice; if you're still using OptiFine with Fabric, and you're wanting this for 1.19.4 — the latest version of OptiFabric available at the moment — then you'll be in for a rude surprise using later copies of Fabric API.

The release of Fabric API last compatible with OptiFabric 1.13.24 is 0.80.0. All mods requiring Fabric API need to be compatible with this version of that, else your game simply will not load as changes in Fabric API 0.81.0 will cause 1.19.4 to crash.

I'll release another writ for 1.20 once OptiFabric is available for that. Else use Sodium. Yeah yeah I know you need more jars and the means to convert mods dependent on OptiFIne so they work without it, but considering the absolute state of affairs for Fabric users wanting OptiFine, grabbing a few more jars and putting in a little extra work isn't all that bad; especially when the result might perform better than when using OptiFIne.