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.


@[email protected] has a comment below stating that some of these are examples where a piece of media did something new and innovative that was so compelling that many subsequent pieces of media copied it, and thus whatever it was that the piece of media did failed to impress later audiences. For them, it was just the new normal. So the work was very influential…but maybe no longer stands out.
I’ve often seen Citizen Kane cited as being the poster child for this.
https://en.wikipedia.org/wiki/Citizen_Kane
EDIT:
https://thecinemaholic.com/citizen-kane-innovations-flaws/
EDIT2: @[email protected] linked to the Seinfeld is Unfunny trope on TVTropes, and it has an entry for Citizen Kane:
Definitely true. I’ve heard the same and it’s another one of the reasons I want to appreciate it.
A other example of this that’s frequently cited and happened in my own life time which makes it easy to see first hand and understand is The Matrix/bullet-time.