you've almost got it there but not quiteLam said:It's normal in this patch.
Think of it this way:
If it takes 100 xp to get the belt to the next level, then level 1 would take 100xp in total, level 2 will take 200xp in total etc.
If you reach level 1 you'll have 100xp on your belt.
To reach level 2 you'll need 200xp in total but since you already have 100xp from reaching level 1 you're halfway there so that's why the game displays it as 50%