I liked ( past tense ) watching YouTube with the latest Firefox on my Mint Linux box.

No more.

The ad blocker I use ( latest version ) has stopped working for removing YouTube commercials.

The commercials are obnoxious.

I think I will quit until the ad blocker I use updates again with a fix.

Sorry YouTube, you are far from being worth $14.00 USD a month.

Edit:

Mint Linux 21.2

Cinnamon 5.8

Firefox 128.0.3

Ublock Origin 1.59.0

• I completely removed UBlock Origin
• I completely emptied my Firefox cache and other data
• I signed out of Google completely
• I reinstalled UBlock Origin
• I signed back into Google
• I tried using YouTube with my VPN turned on.

No joy.

I can watch YouTube ad free via a private window in Firefox.

I can watch YouTube ad free if I log out of my Google/YouTube account

My add blocker works in other browsers when I am not logged into my Google/YouTube account.

YouTube limits ad blocker usage in new test
YouTube could be testing a three-strikes policy for ad blocking (Update)
So its clear now that YouTube is going to limit the usage of Ad blockers in the coming future
I use Ublock Orgin with Firefox which basically used to block all ads and on mobile device I use NewPipe

Relevant part of YouTube TOS that'll come into effect on 2019-12-10:

YouTube may terminate your access, or your Google account’s access to all or part of the Service if YouTube believes, in its sole discretion, that provision of the Service to you is no longer commercially viable.

However, it's not clear whether "Service" is YouTube or whole Google account. As we've seen in Markiplier affair, violating YouTube TOS meant that people lost access to their whole Google account - including gmail and gdrive.