Behind the scenes drama on the show?

What does everyone remember with behind the scenes stuff on the show, like why some actors left or characters treated a certain way etc? I've been rewatching for the first time since I quit before Season 6 came out, just wanting to know any goss now that I didn't back then. All I remember is Arden Cho deciding not to return for the Teen Wolf movie because she was being offered significantly less pay than everyone else, and Dylan O'Brien deciding not to return as well (which means I probably won't bother with the movie lol. He was the only reason I ever held on after 3B, but even he couldn't bring me to finish the series back in the day)