Marvel isn’t infallible. Their latest phase is an example of that. Their numbers are great when compared to other studios, but it has not seen the level of critical success that it once did, despite being somewhat more inventive in its the stories being told. I enjoyed quite a bit of their movies, like the latest Black Panther movie or the third Spider-Man movie, but overall, its really taken a step back in terms of quality in almost every other project they have made. They also lost one of their biggest creative auteurs, James Gunn to their biggest rival, as well as the guy who made their Spider-Man movies and the Russo who made the previous two Avenger movies (though it could be these guys return). Ryan Coogler doesn’t seem interested in doing the penultimate (?) Avengers sequel, they aren’t going to trust Taika Waititi or Sam Raimi or Joss Whedon with that movie. They have resorted to getting Hugh Jackman back for a final (?) paycheck as Wolverine for the upcoming Deadpool sequel and apart from that don’t seem to have a plan on bringing their other most famous IP into their franchise, the X-Men.
And also the other big development is that they have lost the Chinese box office marker, though this seems largely out of their control as China is an aggressive geopolitical adversary of the US and is also strictly against LGBTQ representation, and Marvel is (rightfully so) not budging on the edits suggested by Chinese censors.
And then there’s also the case for superhero fatigue, and I am saying this as a fan of most of these movies, (I watched most of their previous movies during high school and college almost religiously), but the amount of content they dumped on Disney+ which was of varying quality was too much for me to really watch. I skipped half their shows and most of their movies (waited for Disney+ for most of the movies except for Spider-Man and BP2). I genuinely don’t feel interested in most of their upcoming lineup, except maybe GoTG 3 and Captain America 4 (if it’s any good). I might be speaking for only myself here, but I potentially see that happening more so in future with general audiences.