I haven't seen an ad on Youtube in ages - except for a brief window when they got through my ad blockers recently but that seems to have cleared uo.

As far as content goes, I use it logged in, and I have plenty of good content, but of course the default for a logged-out user is going to be generic, trending videos. Youtube like any other social media platform expect you to have an account and curate that account.

Maybe you deleted your cookies or switched IPs recently?