I was in 20210220 fully updated and everything is working.
I decided to upgrade to 20210320. Everything went fine during the (very long)
update process.
After the first boot the system stays in text mode login screen and at the top,
an error message:
[ 6.534238] nouveau 0000:01:00.0: bus: MMIO write of 800001f4 FAULT at 18eb14 [
IBUS ]

On grub menu, selecting the previous kernel 5.10.16-1-default, results in the
same error message. Please check this image: https://imgur.com/a/mp75rtA

Using the proprietary nvidia driver is even worse: There is no text mode to see
anything.

Using the snapshot rollback I manage to go back to 20200220 where everything
works using the proprietary nvidia driver:

My system (after the snapshot rollback to go back to 20200220):

Operating System: openSUSE Tumbleweed 20210220
KDE Plasma Version: 5.21.0
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2
Kernel Version: 5.10.16-1-default
OS Type: 64-bit
Graphics Platform: X11
Processors: 8 ������ Intel������ Core��������� i7-3770 CPU @ 3.40GHz
Memory: 14.6 GiB of RAM
Graphics Processor: GeForce GTX 970/PCIe/SSE2