Dollar Tree review: employee

I visited the brooklyn store on 4/7/2019. I would say around 4:30pm-5pm. Their was a cashier working on the second register and she proceeding to bad talk about another employee to customer who had zero idea what she was bad mouthing about. We come to the store to make a purchase and expect to receive proper customer service. I'm not expecting to get a mouth full of filth from a cashier. What makes the whole experience worse the manager/ assistant manager was there and listening to this employee bad mouthing the other employee who wasn't even present. I'm a retail manager myself and I was disgusted at what I was hearing and the icing on the cake was the manager/ assistant manager did absolutely nothing! For me personally; this should be addressed. If management cannot handle employees and their emotional outburst none should be working period. That to me was unexceptable behavior and I was disgusted by the language and the nothingness the manager/assistant did to stop this employee.