EU leaderboards for new era started recording records before all players where on 2.6.7 patch. This allowed some players to enter new leaderboards with old version of builds ( from 2.6.6 patch, not nerfed).
If you are able to track what client version player used when he finished GR you should remove all records done by players who used 2.6.6 patch.
Or you could reset Era leaderboards again, after all hotfixes.