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.
Gods, I fucking hate time-travel/multiverse plots. They’re so overdone.
They’re basically used for when the writers are too cowardly to stick to decisions they want to make. Like killing key comic book characters. Nobody stays dead! Except for characters nobody cared too much about or has lost popularity. Spin-offs are different and can be used to tell stories of maybe what things would be like if X character isn’t around anymore. That’s fine.
But interjecting lazily implemented multi-verse, alternate universe, time traveling wrenches in on-going mainline stories? Fuck no.