I would have thought that the Rise of the Skywalker would have ended this line of thinking. The Last Jedi made over a billion dollars too and has a high RT score, but because of the divisive fan reaction to that film its now universally agreed upon that films poor reception caused Disney to panic and produce a subpar sequal.
The thing with the Mandarin too is we know that Marvel is specifically aware of the backlash because they produced that short, a in-universe comic, and isn't the 'actual' Mandarin going to be in that Shang Chi film?
Nearly every superhero film nowadays has a cgi boss fight at the end, it has nothing to do with Zack Snyder.Wonder Woman's Ares fight was met with critism by even some mainstream critics. No one felt it ruined the movie just that it felt like Patty Jenkins film got highjacked for a few minutes by Zack Snyder.