Alt-tabbing small window suddenly becoming widescreen (just the small window)

I'm using fullscreen just FYI.
Been playing for 3 days without issues alt-tabbing in and out without the small window becoming widescreen untill today for some reason.

Usually going from fullscreen>windowed>fullscreen fixes the small window and I can alt-tab without it going stretched again until I restart the game where it starts to happen again.

Uninstalling the game and deleting everything in folder under ffx14 fixes the issue.I think just deleting the fx14 folder in documents is enough tho but I tried the nuke method.