I tested if I can hear a difference between a local 320 kb/s MP3, YouTube and YouTube Music by a blind test switching randomly between the apps with closed eyes and then playing.

I used a Snarky Puppy song called Gemini https://youtu.be/XXBaqM_8T6o because I have it in good quality and also it is a jazz song with really good sound production.

The result was that I am able to hear that YouTube has quite a flat sound but I can't distinguish between the MP3 and the YouTube Music stream.