I finally figured this out and it was my own fault. One day I was looking at my Eero app and I didn't recognize what an "espressif" device was, so I paused/blocked it. Turns out it was the PS1Digital, and apparently checking for updates when connected to WiFi but lacking internet access will...
About once an hour, I will get an HDMI resync out of the blue, but only when Force Mode is enabled. It occurs when there are no resolution changes occurring -- for example, during a cutscene in Metal Gear Solid. I've tried to narrow down what triggers it by powering off the system, reloading my...
When I have the PS1D check to see if a new firmware version is available, it waits for a few seconds and then seems to crash/restart itself. The name of the game no longer appears in the OSD after this happens (until I do a full reset)
Currently on version 1.5.3, which I think is the latest...