Flat earthers don't use Mercator projection, they use polar azimuthal equidistant (AEQD) projection centered in the north pole.
I think it would be something like Portugal-Kamchatka:
https://i.ibb.co/9mqz8fvb/image.png
I didn't know that. Makes more sense than a rectangular projection at least.
I didn't know that. Makes more sense than a rectangular projection at least.