The difference between my YouTube interface with and without premium is stark. Aside from the ads, it seemed like the algorithm pushed less slop in front of me to avoid. Purely anecdotal, and likely affected by A/B bullshit (or nowadays would it be more like A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P/Q/R/S/T/U/V/W/X/Y/Z).
Paying to remove Ads means I don't want ads, it doesn't mean I consent to all of the other invasive tracking they do.
If your experience with YouTube is primarily through browser then yeah I can see why that experience is shitty.
I'm fine with sites detecting adblock, in the sense that I will just not go to those sites. But if I already pay for an ad free experience then there's no reason for them to care about my adblock, unless they're just mad they can't track me, in which case, they can fuck all the way off.
And yes, I know that Google is in that camp, so they can indeed fuck all the way off.
Ads are useful and have their place in keeping the web accessible to everyone, but Google's anti user policies really stretch that relationship.