My go to reference for this is Search Party. The first season is the most engaging TV I’ve ever seen, the second season is still pretty damn good, but then the show got picked up by HBO and became total shit for 2 seasons. Like god I fucking hated season 4 of that show.
As far as movies go, I gotta go with Shrek the Third. 1,2 & 4 are all great, but what the fuck was 3?
I’m of the minority opinion that season 4 is still pretty good, at least in it’s original cut, but season 5 somehow manages to be a comedy show without a single funny joke in it.