It seems like upon changing a setting, F1 is toggled on.

This doesn't happen and has never happened to me, so I don't know how I can help.

Huh, that's weird. I don't think I did anything specific to make it this way. It just starts when I open the game and join a world.

Are you only using Legacy4J and its dependencies? It could simply be an incompatibility with a mod

I am using additional mods, that being WorldEdit, LazyDFU, Entity Model Features, and Entity Texture Features. I turned each off individually and tested, and then turned all off collectively and tested (All besides Fabric API, Architectury API, and Legacy4J) but the issue still persisted. If it's any help, I'm on Fabric 1.20.4.

this doesn't happen to me either

There is nothing wrong, you certainly have the Display HUD option in User Interface section disabled and you are forcing the HUD to appear with F1