This is a very Bongland-specific example, but Love Island.
I'm old enough to remember, way back in the mists of time, in the early '00s, when reality television was at its height, and the public's appetite for it was greater than it had ever been and even back then, Love Island was derided as a sort of cultural nadir, bottom-of-the-barrel, the lowest example of the genre, something that even fans of reality TV garbage turned their noses up at - and it was cancelled after a single year.
Fast forward to the Current Year, and the new, relaunched Love Island has become one of ITV's most popular shows.
...It's just kinda weird to see an example of actual cultural decline happen in your own lifetime.