Importing mp3 files to Music degrades quality, especially bass levels are increased

I've noticed this on and off for years, but rarely import new music since I normally stream. Just recently I imported a few new songs, and ran into this issue again, this time with a few fresh files.

In Finder Preview the files sound fine, no issues.

As soon as they start playing in music, either by drag-to-import or just "Open"/double click, it's like they've been normalised, maximised, compressed, all in a random mess that's just... bad.

Volume is increased a bit, but bass levels are turned way up, and then normalised/compressed so they sound loud but super crunchy, clipping. Most noticeable in electronic music heavy on bass and kick.

I've tried different codecs in the import settings, but doesn't seem to make any difference.

First set to AAC/Plus (by default, I think), but tried 256 mp3 as well.

Mostly been using "Rock" or similar EQ for years without issue, no additional volume increase. Streamed music sound fine, so no issues there. Tried with/out Sound improvement (low) and auto Volume level, no difference, but almost worse w/out, so they help a bit when on.

Even senior support were a bit clueless, and said I have to try reinstalling one of my Macs to troubleshoot any further with the engineers.

Anyone noticed any similar issues, with imported files potentially permanently damaged?