A lot of shows should just end with one season, we don't need the backstory fleshed out
This is not to say that seasons after the first one are bad, but sometimes I feel as though later seasons exist because of the show’s popularity and not because the creator had more to say (The Last of Us, even though I love Part II). Also, it’s okay to have an open-ended ending with loose ends, leave it to our imagination on what’s going to happen next (Westworld).
Terminator the Sarah Conner Chronicles ended on a cliffhanger and then got cancelled. I was mad at the time, but now I like it. The show was good, and if they continued on they would have eventually ruined it and turned it into: Buffy the Terminator Slayer.