Hardware issues?

Hi community. I have a refurbed 2020 13in MacAir that about 3mo. ago began to randomly quickly (<2sec at most) flash what appears to be one or more QR codes in random places on my screen. I've tried to get a screen grab but it's too fast. I've also monitored activity monitor to see if I could find a responsible rogue function occurring around the time it occurs to no success. Finally, expecting malware, I installed Sentinel1, which also has found nothing malicious. I've also reinstalled the operating system, run first aid, reset PRAM, NVRAM, etc. It keeps on happening. Apple support thinks it's a hardware problem and has recommended I send it in, but my paralegal is using it for work while I'm waiting for a new iMac and haven't had the chance to get it in yet.

Today I installed Big Sur 11.5, and on restart my entire screen filled with the pixelated QR code like symptom rather than the flash that has been occurring in random spots on my screen. So, I restarted to see if I could reproduce it and got a screen shot before the computer shut down. It occurs right after I hit shutdown, stays on the screen for a maybe 5 secs, and then the computer shuts down.

Here's the screen shot:

Or, maybe not. Apple is telling I can't upload the .JPG and to try again later.

fml ... Is the one dependable brand I come to depend on in the world going to the dogs as well?

Can't even host a functional chat forum for crying out loud.

I guess I'll try to post the pic later down thread.