It's literally louder in IMAX. I cited seeing it in IMAX because the "problem" is exacerbated there. With TDK the articles were about how they switched from IMAX cameras during dialogue scenes because of how loud everything is when filmed in IMAX meaning dialogue could get drowned out. After TDK more and more Nolan films stopped switching from IMAX, though even TENET occasionally swaps to regular film like when he's talking with Michael Caine, the only dialogue that passed people by would be things shouted back and forth in action scenes, which is fine. I'm fully aware people are complaining about this, but they're wrong. Anyone thinking there was a line of dialogue they missed that was the "key" to understanding TENET is full of it, you either got it or you didn't, try seeing it again. I'm not even joking about them deserving a sound mixing Oscar or "trolling", action movies should be loud, the things I wanted to hear were loud, the audio experience of TENET is as exciting as the visual one as a result.
Paradoxically people complain about too much expository dialogue in Nolan films while also complaining they didn't "get" the film because they missed a line of dialogue... either you can "get it" without all the dialogue being audible or not, but many people want it both ways. I honestly think the average psuedo-intellectual when seeing something like say Inception, hears the explanation and says "Oh... I probably could have figured that out, I didn't need that dialogue" when the truth is without that dialogue they would say "it was too confusing". Some people think it's Nolan taking criticism to heart but again... since Inception his films have been this way, Inception got away with it easier because of how many non-noisy scenes of exposition it has (which is because it's framed as a heist film with planning scenes, also because it's a movie about movie-making and we're seeing how a movie would be planned as well) versus a film like TENET which is far more aggressive in its pacing with less downtime, it's framed more like a Mission Impossible film where the down-time is small bits of planning/justification for action scenes that are akin' to franchises like Mission Impossible in how thin they are in justification and audience understanding.
The average MI film is some crap about a rabbit's foot or something and the audience is just along for the ride, he doesn't elevate it by eschewing the minimal justifications for the next big set piece but by making the effects of the doomsday device felt throughout the film (all the inversion) causing the possibility of calamity to seem more likely while also making the action far more interesting. He took a movie like Primer or Predestination and turned them into Mission Impossible films. To be fair, yes, most people wouldn't get those movies if lines of dialogue flew by them but Nolan isn't interested in having you 100% understand a concept, I've seen people complain he never even explains how reversal is possible, but he also never explained in Inception how the shared dreaming was possible. The film's establish what can be done and explain the rules, but not how.