At the risk of you guys either laughing or scoffing at me a bit, the issue I was having is gone. I had the system freeze problem for about a month before I finally called for help on the forum, and it literally stopped happening basically as of yesterday. I will definitely look at the system log should it happen again.
New cable has made no difference unfortunately. Another oddity is that when I scroll left or right through the emulators (and the transition style is set to 'fade') the red pixels all disappear and only reappear when I stop scrolling.
It's not the biggest issue, just would like to understand what's causing it so I can learn a bit more about it.
Does it get cleared on restart? As I have rebooted several times since the issue above.
Yes, /dev/shm is a RAM backed folder, restarting would clear it. The file is present after the game is run and it's also overwritten each time a game is launched, so if you want to get the actual error, you need to get the file immediately after the crashed game stops.
@rilight I was actually looking for that thread before posting this, I could not find it for some reason. I am disappointed that this is happening. I will also look for the screen tearing. I will probably hold off on swapping my Pi3B+ out of my arcade cabinet for this Pi4 until things are smoothed out.
I am using Carbon with no modifications to any settings, fresh image installed from this website.