Good thing you already checked cables, but did you also check that there are two GPU cables connected to PSU and GPU and not just one cable starting from PSU and split into two which connect to GPU as this kind of 'daisy chaining' is not a good option and can cause issues.
Next question would be your PSU's brand, model, wattage and age.
Also try switching monitor cable to a different port in GPU and monitor and perhaps try with DP or DVI cable for testing.
Have you kept an eye on GPU's temps in case there is something wrong with the cooler?
I would also unplug GPU and reseat it to make sure, it is properly installed.
Then you could try with Smart Access Memory enabled and disabled and consider updating BIOS.
Maybe try connecting PC to another monitor or television for testing, if symptoms disappear.
You could also try Windows power saving settings - PCI Express -> Link State Power Management -> turn off
Some people have issues with Windows 11 updateing driver by itself. There is a fix for that too.
