yup I've been noticing that and it's really annoying cos I can't use the super steady cos of the quality drop. here's an example with and without super steady on and off
I noticed this on phones a while ago. Mainly Samsung's and Sony Xperia phones too. I never use for that reason. I also don't see any difference with HDR turned on or off but I'll need to test further.
I thought it was just me, I use super steady quite a lot and all I got from s21u so far is grainy video. Even worse is low light photo and video they are smudged. hopefully this will be resolved in a future update