Saturation is definitely still broken. I just installed a bunch of brown mooshrooms all over my base, fed them blue orchids, and found that the resulting suspicious stew behaves identically to mushroom stew.
If moss gets a net gain of bonemeal, I have no idea why nylium can't. Nylium-based bonemeal farms are relog-proof (unlike the moss farms), satisfying to build and use, and were one of my favorite 1.16-1.17 features.
Saturation is definitely still broken. I just installed a bunch of brown mooshrooms all over my base, fed them blue orchids, and found that the resulting suspicious stew behaves identically to mushroom stew.