I just downloaded the new Windows build, and the map seems a little wonky? See the upper right corner.
I don’t see anything in your screenshot. However there seems to be a bug where the text from the map legend (road, unexplored, forest. plain, etc) doesn’t disappear while you’re moving on the map screen. Do you mean that?
He probably meant that “black F on blue background” thingy. Are those megastores? So many of them!
Abel seems to be right. The F’s are 'fema camp’s. Not sure what that means but I will find out soon 
what’s FEMA? And why they got camps all over the place? 
Known bug, I was hacking on the overmap display until midight last night and finally gave up so as to not delay the release. Will be looking into it, along with htat weird white bar and the orange questionmark.
Thanks for reporting though.