I think it’s referring to the “you can’t block ads on YT or we might ban you” popups you get on YT occasionally, if you’re using an adblocker. I have only had it happen once or twice before I did a quick online search and found an extra filter or two to add to uBlock Origin, and then I stopped seeing them.

I wonder how much time their devs spend working on a new ad block detector scheme that gets shown to a couple dozen people before ublock origin adds it to the default filters and none of their users see it again.

I wonder if they get frustrated or just laugh and get back to the endless job. Or if they also write some of the ublock filters themselves.