GPD Pocket 3 screen flickering after standby


My Pocket 3 i7 has a screen issue : when the laptop goes in standby mode, sometimes when I wake it up, the display is flickering and there is a huge dark oval in the background.
My non-specialist eye sees a backlight driver issue (either software or hardware).
Rebooting it does not fix it, but if I use it long enough, the flickering and the dark oval disappear over time. Shutting down the computer for some time fixes it too.