🎀Installation:
Download the latest release of GBFRelinkFix from here.
https://github.com/Lyall/GBFRelinkFix/releases

Extract the contents of the release zip in to the game folder.
(e.g. "steamapps\common\Granblue Fantasy Relink).

🎀Configuration:
Go to the game installation path, in the (script) folder
:\SteamLibrary\steamapps\common\Granblue Fantasy Relink\scripts
and open the GBFRelinkFix.ini file with a text editor, even notepad is fine and modify the highlighted parameters, as in the image:
My primary monitor for example is 3440x1440, you will have to enter your resolution.
Now open the game and have fun!