There's been a trend over the last 15-20 years as the big US movies have internationalized of reducing dialogue complexity to enable localization (once you notice it, the lexicon and grammar complexity in recent-ish Marvel movies especially is crushingly limited). Maybe mixing poorly (and writing a movie with "you won't really hear or understand the dialogue" in mind) is another strategy to hide that.

That, or a cynical mix engineer noticed that the words don't make the movie any better, so they made an editorial decision to cut them a little (plus, everything was clear enough in their carefully calibrated 22.2 Atmos studio).