Hi,
Well …long story short - like in the topic. No videos from YT (after last “walk-around”) are working - I noticed it today, just like an hour ago 
As it is bedtime for me, I will try to post logs tomorrow - but if anyone has the same problem, please do post.
Cya tomorrow …zzzz 
Ok, I just downloaded the update (not even manually, but via the same repo I have for long) and now everything works OK 
…I was scared a bit because this change collided with (a friend showed me that as I use “walk-arouds” like NewPipe [mobile], FreeTube [desktop] and YT plugin [osmc]) YT policy to prove 18+ via ID/credit card (WTF!!! …and a big F U @google and big-tech!!!)
…all in all - thanks for the hint (my auto-update is OFF as 19.1 crashes when playing HEVC files) - normally this would solve itself 
heh…