Knebworth blu ray sound vs cd sound

Probably because the digital audio version was mastered almost exclusively to be consumed through streaming platforms with cheap earbuds, and the same mastering made it onto the CD version.

I looked up on the Dynamic Range database and the DVD version has far better dynamics than the CD version:

dr.loudness-war.info/?artist=Oasis&album=Knebworth

I'm sure there are tools to extract the audio from the Blue Ray yourself, or have a look on Soulseek, perhaps somebody has done it already for you.