triche
Moi aussi, il y a une personne qui avait que 890 elo mais apres sandbox victoire, il a recu 200 elo en plus
If you suspect another member of using disallowed resources, you should report them directly to staff.
https://support.chess.com/en/articles/8562517-how-do-i-report-someone
That said, discussions about cheating, potential cheating, or cheat detection are not allowed in the general forums