Android 12 update rolling out to S21 Ultra and others
It appears sometime yesterday the Samsung Galaxy S21 Ultra update rolled out to at least some T-Mobile customers, possibly others, not commenting on the rollout as all I know is that it showed for me.

The changelog link was bad, but a whole lot of things were updated with 12. Update took about 21 minutes from start to usable, and then it kept doing updates on various things in the background as well as T-Mobile’s crapware service attempting to install preselected apps, which thankfully I was just able to skip and not have to deal with removing everything.
Camera seems to have been updated and seems at once both faster and slower. Faster to ready, slower to snap into focus. Could have been the day or just things still updating however.
Not had a lot of time to play with this, but what I’ve noticed so far is accessibility button popped up and I had to figure out how to disable it (colorblind mode is an accessible feature, disable in that area) no more titles on the slide-out side launcher that comes with the S21, T-Mobile icons changed slightly for 5G to 5GUC when you’re somewhere with Ultra Capacity.
Overall, it’s a thing… it’s showing on T-Mobile, my bet is it’s elsewhere as well