In my opinion, this comes down to which part of the 90s you’re talking about, and what sub-genres you’re referring to. In the original post the late 90s was specifically mentioned I think. What sticks with me from that era (actually from the mid 90s well into the 00s) was studios that were recording big-label bands getting caught up the “loudness wars” BS going on in the radio world. I get ear fatigue pretty fast listening to something like the Chili Peppers from that period. Pretty squashed up, no dynamics, pushing the levels right up to the edge. So much music from that era suffered as a result.
On the other hand, the indie bands that proliferated in the early to mid 90s that made up so much of the sound of that era were the ones that ushered in a lo-fi explosion beyond what was confined to “college rock” in the 80s, with bands like Pavement, Sebadoh, Mudhoney, Breeders, etc sticking with that approach even after they jumped from garages to major labels.
So it’s hard for me to even identify a distinct “90s sound”.