As I said, reinstalling Windows had absolutely no effect. And I’m not aware of any issues with drivers. I’m using the official Intel and nVidia drivers. To my surprise, I eventually solved the issue by reflashing the motherboard BIOS…. Yeah.
If I haven’t witnessed it twice, I wouldn’t believe that a driver bug could somehow alter the BIOS (or EFI or whatever it is).
So, just for the reference, if anyone encounters this, I downloaded the Asus winflash utility, the latest BIOS, run the utility with /nodate parameter so it would allow me to reflash the BIOS with the same version and after the BIOS flasher finished, Windows booted normally with the nVidia GPU working again! The blue screen error was VIDEO_DXGKRNL_FATAL_ERROR