My personal sign is when you start seeing awkward collaborations start cropping up. One time when I was thrifting, I picked up a graphic novel that had the Justice League, team with the Power Rangers of all things. I glimpsed into what the plot was about out of morbid curiosity and it was just a plain generic time and dimension thing.
Nothing ever connected between the teams at all. DC Comics, while fledgling at times with how they go about their series and movies, still have far more relevance than Power Rangers do. I think the Power Rangers are just grasping at straws to keep being relevant when people have largely moved on from them.
Meta: when the principal actors become the producers.
When the sexual tension between main characters eventually results in a sexual relationship or they get married.
If it’s Cop apologia, when the cop has to go ‘rogue’ to get ‘justice’.
I find it worse when the sexual tension just keeps on going and goes nowhere. I really liked for example that they didn’t do that in Kim Possible. They let Kim and Ron become a couple and made new stories about how they work out as a couple. It’s been a while since I’ve watched it, but I remember appreciating that they could just be together instead of some will-they-won’t-they bullshit.