On December 17/18, the Security update KB5008215 (OS Build 22000.376) has been installed on my Dell Alienware X17 laptop. After that, I've been experiencing the following behaviour:
Every few seconds, the screen blinks as if the power cable is (dis)connected, despite the cable being always in.
Several seconds after the blink, the screen stops refreshing. I could force the refresh by actually plugging in and out the charge cable. After that, the mouse is shown as moved in the direction where it has been moved, and typed text is typed. That is, the devices send and retrieve information, it is only the scree that freezes.
Rolling the update back restored the normal functionality - thus the behaviour is neither a virus no machine malfunction, but is caused by the update.
I hypothesize that the update forces my machine to constantly check whether the charge cable is plugged in.