Warning: This is about to get very nitpicky, I am aware.
Ever since the XP bar was introduced, that and everything above it in Minecraft Bedrock has been off center by a pixel or two. Don't believe me? See this screenshot, zoom in, and you'll see it:
It's just kind of bothering to me how this is like this and no one thinks to fix it.
While we're at it, I would also like to suggest adding the black outline around the XP level to match the Java and Console Editions of the game. This would also make it slightly easier to see the number against backgrounds of similar color.
These two changes would make the Bedrock UI feel much more Java-like and more comfortable for transitioning players to use.