Thank you for all your advice!

Yeah, I wasn't entirely sure about the type of border or what to do with it, I'll try to simplify it as much as possible.

I am actually thinking of removing the stock compass completely for now at least.

As for the "white sands" next to the coastlines, I'm thinking of removing the white glow and continuing to lighten the coasts a bit like how I lighten the colours of the seas as they get closer to the coast.

As for the mountains, I'll try to darken them and make them a bit nicer. Maybe using dark brown instead of black(?) And likewise turning the trees dark green? Or maybe improving the shading? I'll experiment a bit with all that.

I'll try to improve the map a bit later, thanks for all your information!