This was the only thread here I could find about this issue but over on Macrumors there is a large ongoing thread about this. Most of the complaints are from those with the new M2 but I, as well as others, have seen this on the M1s as well. The determinate issues are having night shift, True Tone, and dark mode all on. Turn night shift and True Tone off and there is virtually no issue even when dark mode is on. The vast majority of posts, and my experience as well, popped up after 16.1 was released. Those who were able to avoid 16.1 or downgrade from it are not seeing any such issue.
Most of us maintain that it’s a software issue but a fair number have gotten replacements with most stating the issue is present on the new devices. Also quite a number of people have gone into Apple Stores and checked the display iPad Pros and state that the issue is present on them as well. If it is a software issue a timeline for a fix is unknown. 16.1.1 does not address this.