About one sixth of the bottom of my screen keeps flashing black every few seconds, while the system speaker beeps. Completely unsure why this happens only when fullscreen is enabled during startup, but I can keep replicating the error, and have attached a console.log of when the error had occurred. It's not the refresh rate, I play all my other games at 75Hz, and experience no issues with them.
Changing my prefs to disable fullscreen is a fix, but I would prefer Blockland to start up in fullscreen instead of me having to enable it every time.