I don't know if it's a trope, but I definitely feel like it's becoming one: When a TV show has one random episode that is stylistically completely different from the rest of the show. These episodes are generally artsy/experimental and well-reviewed but by they drive me up the wall since they stop almost all rhythm the series has.
Examples:
Fargo S5: Puppet Show Episode
Ted Lasso: Coach Beard episode
Bojack Horseman: Lost in Translation underwater
Barry: ronny/lilly
I'm not saying these episodes are bad, in fact some are great, but they also aren't the show I wanted to watch. Especially since seasons are only like 10 episodes now. It made more sense to be experimental when there were 24 episodes a season.