I have a 7.1 system, unfortunately, this is an issue here as well, that I will argue grew worse since Atmos started becoming mainstream.
Particularly in the mid-to-late 00's, centre speaker dialogue was very bombastic and stood out very well even in high action scenes. Yes the volume was still sometimes mismatched, but not to the point a discreet multi-channel setup needed to constantly adjust volume. Films from the previous two decades had even less issues just thanks to the simplicity.
Atmos feels like a huge wasted potential to me personally. With the added height channels, you can create some amazing effects and absurd imaging that was never possible before, but the reliance on this kind of swerved sounds and vocals to overlap each other in more awkward ways that makes it feel like everything is originating from a reverberation chamber. Particularly with dialogue, Atmos helps create positional ambiance with indoor scenes, so vocals often sound muddier than they should be.
Even worse, streaming services provide a mix that obviously caters to handheld devices, TVs and soundbars, while being Atmos 7.1.4, sounding particularly terrible for both kinds of watchers. Blu-ray's thankfully still often directly target home theatres and sound much better for the latter.
That's just been my experience so far. Going from a simple 5.1 Jamo from 2007 to an upgraded Atmos setup, I've been blown away far less by action films these days. It's even amazing if you hear the rears getting utilised at all.
Same here, I've noticed that mostly since the point Atmos started becoming mainstream, movies just aren't mixed like standard films from the late 90's to 00's. Sure, we didn't have overhead sound sources or admittedly fantastic imaging for the few films that do it right, but overall, everything sort of feels like a narrow, bland tunnel tuned for soundbars / TVs, for which neither Home Theatre nor Soundbar owners enjoy ironically.
The "Enhance Dialogue / Reduce Loud Sounds" feature on the Apple TV has been amazing for helping to rectify this, but I would prefer to leave the dynamic range of the track alone.