Xp Level Command Not Working

When I Use This Command It Helps Me A Lot On Maps...Then When 1.16.0.60 Started The Bug Occured. I Ignored It Then After Some More Versions I Realise to tell this bug to be fixed...

Example :
/xp (Amount)L or /xp (Amount)L @(choose)
doesnt work...it is just continuesly saying the player target...
same bug with 1.2,but updated version now...different user