Epic clearly did not expect anyone to succeed. That’s why the interface behaves in such a strange way.
Several dozen hours ago, Fortnite players managed to break the world record for the highest level. Reaching level 1000 was not spectacular. It turns out that it gets more interesting when players cross this barrier.
Epic apparently didn’t predict that anyone would ever get to that level. So the interface just bugs, showing 0 XP and level “X”.
What does it look like when you go over level 1000?
The developers have not prepared for such an eventuality, which is why Fortnite does not know how to approach it. In effect, “level X” is shown on the left, instead of the correct level 1001. In addition, the wrong amount of XP is displayed at the bottom, which is exactly 0.
It will probably be fixed soon, supposedly in the next update. The error currently affects two people who have reached the 1000th level.
So this is definitely not the most urgent matter that Epic has to deal with right now. It should be treated more as a curiosity.