I see that the support for toggling the overlay for mushroom bioms was removed again.
Is it just something you don't want to have? Or something in the implementation wasn't right and needed fixing?

If it's the first OK I wont bother you any more. If it's the second would like to work with you to make the implementation better.

It is no longer possible to detect mushroom biomes on the client anymore since mojang made the biomes data based.

oh, I didn't know that. how annoying.
It looks possible to extract the information some other mods are displaying the bioms.

I'll look into it.

the old code minecraft.level.getBiome(pos).getBiomeCategory() == Biome.BiomeCategory.MUSHROOM seams to work both on servers and locally on 1.17.1 I haven't tested with 1.17

That doesn't take in account the actual biome spawn settings, and unfortunately, some servers don't seem to send that.