The main driver IMO is the death of the tight 90 minute, 80 Million decently acted thriller / action / comedy film.
Everything is too big, too epic, too simplistic, and too long.
If I understand movie theater economics correctly, the studio gets 80 to 95% of the ticket sales, depending on how "first run" the movie is. The theaters actually make their money on selling concessions.
Well, the longer the movie, the more people feel the need of snacks to get through it. So maybe the theaters are pushing longer movies rather than shorter, because they make more money that way.
Bit of a tight line to walk. Longer movies mean fewer showings per day. When I saw that Oppenheimer was three hours long -I want to watch that at home so I can take a bathroom break/snacks so a personal pause button is an improvement on the theater.
It used to be fairly common with the big "epic" films. And probably no live theater production is going to go much over 90 minutes without an intermission.