Random issue, screen garbled after time

[TDMPro2K]

Hi all, need abit of help. My mirror has randomly started going garbled on the monitor for no reason randomly. I thought it was the pi itself and I have bought a new one and redone it. However it has appears to come back.

I’m on now pi3b+ with a new 3a psu. Fresh install on latest mirror build.
I have restarted the monitor with out turning the pi off and that doesn’t sort it. The only thing that get it back is a full reboot of the pi.

Any ideas?

Here a video of it
youtube