For me if I had to pick a good contender it would be the UK version of The Office.
I know many tend to debate how Ricky Gervais really fell off and how he repugnantly acts like a whiny centrist edgelord but me personally IMO I actually don’t think he was ever funny not even a little.
His big break through television was just so painful to sit through it’s so charismatically boring the characters are completely generic at best (notably Tim) or straight up insufferably unlikable at worst (especially the protagonist David FUCKING Brent) and most importantly the humour is just embarrassing.
Always seemed like The Thick Of It but without the nuisance tongue in cheek and charming satire.
Oh, I have no doubt there’s some Seinfeld is Unfunny effect going on.
But unfortunately I read it in ~2020 after three decades of reading books, so every plot beat was played out for me beforehand by decades of imitators who iterated on it. Unfortunately, being first doesn’t make me care about your plot.
This makes me think about The Belgariad. It seemed like a tired rehash of old tropes at first…but those tropes weren’t so tired when the author wrote it. I enjoyed it quite a bit more with that in mind.