The bug
The dot and small dot out-of-border map icons are rotated by -45 degree compared to how they appear in the map_icons.png
file.
Yeah, I could just turn the icon in the texture, but that's 50% of the solution, because it might be fixed in a distant future, and I'll forget to turn it back, etc, etc..
How to reproduce
Download the attached resource pack
Create a map and leave its borders
❌ The shown out-of-border icon has the red corner in the top right, while in themap_icons.png
it is in the bottom right
Does this also affect 1.10.2?