It's working fine on Youtube in Optimal mode. If you have still issue, you will have to go through self-diagnosing steps[1] to rule out all the myriad other ways you suffer such issues -- most commonly another extension is interfering negatively.
uBO being so good at blocking YouTube ads to the point where you didn't need to signup for Premium may have been the tipping point for Google that ended manifest V2.
i suspect that youtube mobile is responsible for more traffic than web. And that it's harder (but not impossible) to have adblocking on mobile (such as revanced).