Reports are conflicting, with some players saying that it’s purely a visual bug and that they’ve maintained their original rank – but not all players are that lucky.
Others are reporting that they’ve lost their previous rank and, in the worst cases, that they’re stuck at Rookie IV and unable to gain RP.
It’s currently unclear what’s causing these massive demotions or if it’s possible for players’ ranks to get reverted to what they were. This bug has been the source of much player frustration, with their hard-earned rank getting erased without explanation.
References: https://answers.ea.com/t5/Bug-Reports/Rank-resetting-to-Rookie-Users-gaining-0-RP/td-p/12302439
