No need to do it. I’ve been logged in and using with no issues. Absolutely no ads, no warnings, etc. But it may also be content. Like I don’t watch the YouTube TV stuff that says “free with ads.” I know when I tested earlier, I was able to watch without seeing ads but I’m assuming they’d kind of be more aware of that and have a higher chance of getting at people for those things.
It’s just as with all things in life, it’s a constant battle on technology. There’s a lot of money at stake, so places like Google/YouTube are trying to figure out the best approach. And yeah, if people get hit by the notices or see issue, then means be smart and break from it. Can try to clear cookies, update things, etc. Can kind of figure out what it is that they are picking up on.