I noticed that I was having problem with my Nvidia GeForce GT 730 graphics card: I’d be working then suddenly the screen would go dark followed by a Flash and then resume normal operations. The problem would randomly occur. This is NOT good for someone who is an epileptic. Back in the days of CGA monitors 
I had a Grand Mal seizure that was so violent that it ripped the muscle right off the bone in my upper left arm, and I have not forgotten that.
I figured this “flashing” was due to some bug in either CentOS 8.4, or openSUSE, or a test version of Rocky Linux. It was not until my sister was cussing up a Blue Streak about having the same problem on her Windows 10 machine and when I asked her what graphics card she had running and she said a GeForce GT 730 I suspected that something may be wrong. When Somerville Tom who also had a similar problem with a GeForce GT 730 I knew I had to get rid of that card – I can not afford to have another Grand Mal seizure precipitated maybe by my graphics card. IF you happen to have a GeForce GT 730 and you are having this “flashing” problem it could be due to the driver, or any of a number of things including refresh rates or some other thing. It also might be the card itself.
I just bought a NEW graphics card that I hope will take care of the problem: An Nvidia GeForce GTX 1050 Ti w/4GB of GDDR5 VRAM made by ASUS. It was allegedly here in the United States but the Tracking Number says Taiwan – pisses me off to no end, as I bought it because it specifically because it said “Ships from the United States”. Hopefully it does not take 2-4 months to get here as other stuff from China has taken. BTW depending on how you define “cheap” and “expensive” compared to graphics cards that cost well over $1,000, and most costing in the $400 - $700 range, at $269.89 this was a good buy, that said it still cost far, far more than I would have liked to spend, given this is Workstation, not a Gaming rig, or Multimedia rig. That said living in the Age of a Global Pandemic, where everything is done over ZOOM, Skype, or some other video conferencing mode, a graphics card with a little more “OOMPH” can’t be a bad thing… so long it stops “flashing” 
me.
D’Cat