It appears that the behavior is unchanged versus 23w42a.
They were set to Minimal! Somehow the setting carried over from my modded 1.18.2 instance. That's embarrassing...sorry for the false alarm.
Did you reset the previously generated chunks? If you went to the biome in the prior snapshot and didn't reset the world or those chunks, then of course it will look the same as it did before. This is not a bug. I've attached two screenshots; they are of the same mangrove swamp area on my world in 22w14a versus 22w15a. Note the deeper mud and tweaked tree generation in week 15.
Uploaded "after" screenshots of the two formerly affected areas in 22w15a. Looks awesome! Thank you 🙂
Issue still persists through 1.21.3.