Windowed fullscreen not staying with restart

I run POE2 in windowed fullscreen but everytime I restart the game I have to go to the options to set it back from fullscreen to windowed fullscreen.

I've been having the exact same issue.

A workaround is to update the config file manually in your My Games folder and then mark it as read only. It has been loading as borderless fullscreen for me since then.

File is here: %userprofile%\Documents\My Games\Path of Exile 2\poe2_production_Config.ini

Set these under [DISPLAY]

fullscreen=false
borderless_windowed_fullscreen=true
resolution_width=2560
resolution_height=1440

Change the resolution to match your monitor.

it's probably nvidia. If you let the nvidia software optimize your graphics setting it changes it to "fullscreen (recommended)" at every start.