I can't honestly say the sound on my 23 AT4X is better or worse than my 2020 AT4 was. The sound is good enough for me, most of my music is stuff I download, and usually it is smaller files, so the music isn't high fidelity. But it sounds fine to me.
I have a streaming kit set up in my truck, which allows full Android to be used through apple carplay. The kit cost me $200, and I love it. My phone auto bluetooth connects to that streaming device, which is hard wired like an android auto or apple carplay device with the mini usb C plug. I noticed the audio sounded a bit clearer through that device than directly from my phone bluetoothed to my truck. Dunno why, but not complaining.
As far as bass, it seems fine to me, but I am not looking for molar rumbling bass. I do have my bass set almost to the highest level, as I usually do on my vehicles, but it is fine for me. My ears aren't the best after 30+ years of being a contractor (never worn ear protection as much as I should have), so my hearing probably isn't as keen or sensitive as others may have. So maybe that is part of why it sounds fine to me - I can't discern subtle differences well. If I think to notice, I always have a ringing in my ears (mostly my right ear). I have had hearing tests done several times about 3 years ago, and while it wasn't great, the test said it also wasn't really terrible either, but definitely degraded somewhat. This was in an enclosed hearing test cubicle, wearing headphones FWIW.