https://www.slashfilm.com/673162/heres-why-movie-dialogue-has-gotten-more-difficult-to-understand-and-three-ways-to-fix-it/

I sympathize with most of what they’re talking about, but I disapprove of their attempt to throw Frank Herbert’s world-building under the bus for Dune Part 1’s dialogue issues. That’s really on the actors. The easiest characters for me to understand in terms of dialogue in that movie were Duke Leto (Oscar Isaac, some stage experience plus prior sci-fi experience plus voice-acting experience) and Chani (Zendaya, singing experience, by extension at least some stage experience, also some sci-fi experience). The hardest to understand were Paul (Timothee Chalamet, practitioner of the Meisner technique, which values improvisation, emotions and “authenticity” above wording), Lady Jessica (Rebecca Ferguson, ESL speaker), and Stilgar (Javier Bardem, ESL speaker).