Cardi B Appears to Diss Stefon Diggs at Concert, 'Who You Playin' With Mothaf***a?'

Cardi B might've backed Stefon Diggs after BIA's diss, but don't get it twisted ... she's still big mad at the NFL star, and she proved it at her latest concert, throwing major shade at her ex! The "Imaginary Playerz" rapper was onstage during her…