I've recently had problems with YouTube. I can watch videos, but there's a message saying that an error has occurred (this happens on my work PC, my laptop and my friend's PC, but he lives somewhere else). I haven't changed anything in my settings. Reloading the website then helps.
In addition, despite the ad blocker that has always worked so far, I get advertisements in front of the videos that I can't skip.
What can all of this be?
Update your browser and addons if you haven't already.
Try another ad blocker. For example "uBlock Origin".
Google and YouTube and many others have sent their employees home, so the algorithm works practically without human control and correction.
There are practically no IT staff there to correct mistakes.
A link about the YouTube algorithm:
https://www.tagesspiegel.de/wirtschaft/wegen-des-coronavirus-youtube-setzt-uploadfilter-ein/25652248.html