ok, I tried. I reinstalled the newest driver (which was already installed, dated 15.06.2022)
-> did not work
BUT
I thought, 15.06 is quite new, so maybe thats the reason
so i installed an older version (GeForce Game Ready-Treiber WHQL 472.12 September 20, 2021), and
NOW IT WORKS AGAIN

so thank you for guiding me to the right path, and for information if anyone else has the same problem with the newest nvidia driver