So, the other day I first completely removed the KB5003690 update and the BSODs finally stopped: the computer has been running for hours without any problems.
So, just today, it came automatically and I installed the July (2021-07) monthly rollup update KB5004945.
For the moment, after nearly 10 hours of uninterrupted activity, no BSODs have occurred.
I don't know how long this (lucky?) situation will last, but for the moment it is.