Monterey does not work for a couple of things on my iMac
When the email reader shows a message only part of the picture shows. Usually just the text. Looking at the same message on my powerbook with Big Sur, the whole items shows.
On some web pages I click on log in or something and nothing happens. The Powerbook works just fine.
Other things are somewhat annoying because "improvements" make things worse.
iMac Line (2012 and Later)