It's not just compression. Rick Beato has talked about this a lot.

Popular music no longer has any key changes:

From 1960 to 1995, between 20% and 35% of Billboard Hot 100 number one hits in any given year contained a key change. Around the turn of the millennium that rate started to dip until it hit 0% by the end of the 2000s. [1]

I believe that simple 4/4 time has also become more prevalent as compared to more complex time signatures. I don't have as good support for this claim, but the AI tells me "4/4 (simple quadruple) has dominated Western popular music since at least the 1960s, and corpus work suggests that compound and non‑4/4 meters have become less common over time in mainstream styles, implying an even higher proportion of songs in simple 4/4 today.".

Beato is also fond of pointing out how modern music is written by committee, and that modern artists are more a "product" than ever before. From memory, he's pointing out that in the past, the credited writer of popular songs was usually a band, or perhaps a single person. But more recently, the credited writer is a list of multiple people not the band (and in fact, top songs across recent years have been notable not under the name of a band, but of an individual performer).

EDIT: Further querying leads to this as well:

Timbral Variety: The "texture" of sounds. In the 70s, you had a mix of acoustic, electric, and orchestral layers. Studies show a "homogenization of the timbral palette" since the 1960s peak.

Lyrical Complexity: The vocabulary and reading level of lyrics. Analysis of Billboard hits shows the average reading level has dropped from 3.5 to 2.7 (roughly 3rd grade) since 2005.

[1] https://www.cantgetmuchhigher.com/p/revisiting-the-death-of-...