The bug
The square which displays the world loading progress becomes black after 100%.
[media]
MC-142692
World loading progress becomes black after 100%
Resolved
Fixed
7
Confirmed
UI
Minecraft 19w03c, Minecraft 19w04b, Minecraft 19w05a, Minecraft 19w08b, Minecraft 19w09a, Minecraft 19w11b, Minecraft 19w12b, Minecraft 19w13b
Minecraft 19w14a
Retrieved
Additionally (this is a bit more of a suggestion), some sort of border could be added to that square to separate it from the GUI background, as right now it looks a bit like it came out of nowhere.