You don’t need to store any cookies to detect adblockers. I don’t know what method YouTube is using but a trivial method is to simply track which of your requests are passing. If all of them are fine except for all the tracking and ad scripts, you can be pretty sure that there’s an ad blocker. This works especially well for pi hole or whatever, because blocking requests is the only method they have for blocking ads.
You don’t need to store any cookies to detect adblockers. I don’t know what method YouTube is using but a trivial method is to simply track which of your requests are passing. If all of them are fine except for all the tracking and ad scripts, you can be pretty sure that there’s an ad blocker. This works especially well for pi hole or whatever, because blocking requests is the only method they have for blocking ads.