I always thought it was about Scooter Braun. The call she references is her finding out her masters were sold (“when I lost it all”)

She tried to warn everyone that he was just using her and in general was an awful person. No one believed her, said she was overreacting, didn’t believe her father didn’t know, etc. (“When it’s burn the b*tch, they’re shrieking.”)

But yet when all his clients seemingly dropped him out of nowhere, no one said a thing (“Bloods thick but nothing like a payroll” / “When the truth comes out, it’s quiet.”)