Ubuntu 19.10 login stuck on purple screen at login

This is not a proper question but might be of help to someone with the same problem.

Every time Ubuntu updates system files under 19.10 I get a purple screen at login without the login prompt.

I found out that the Nvidia card at boot switches to a hypothetical second screen, sets it as primary and shows only the blank secondary. When I move the mouse to the right, the mouse pointer appears coming from the left side of the screen - hence there is a second screen to the left of my laptop that I can't see. But I can access it, typing

Enter (My login password) Enter

and Ubuntu starts normally. the first time it happened it also showed me a blank desktop since also in GUI the primary desktop was the not-connected second screen. Changing the screen options on the laptop via shortcut (Fn - F5 or F6 in my case) restored the single screen. I the changed the screen options to single screen again and I'm safe until the next update.