Bug in Lichess new feature with crazyhouse

Hello,
I have noticed that now when you click on a variant in your profile you can see your progression curve for this variant. However, the for the crazyhouse, the graph opens but the curve does not appear, as if it were transparent...

Indeed, that's a known bug, will be fixed soon.

If I may ask, what is the cause of this bug? Bugs are always fun.

Some styles in the chart are getting re-used (Bullet/Crazyhouse, Rapid/Ultrabullet) which causes that the arrays containing the styles to have less elements than there are charts. The correct style was supposed to be filtered out by index and that wouldn't work for Zh and Ultra, the last two elements in the array with the charts, because their indices are higher than the styles array could take.