Monitor Settings Reset On Sleep (Laptop and external via Thunderbolt)
On my system, I have a laptop that outputs to a secondary monitor (via thunderbolt) I set and use as primary. I then set the output setup to be external only (laptop screen is off). When the laptop goes to sleep in this configuration, it defaults back to extend, meaning I have to set to output to external only after. In my experience, settings like these typically persist on sleep and even restarts.
As a note, I'm on gdm 3.34 (Arch latest) on wayland using intel integrated.