Dollar Tree

On 6/9/2021 at Dollar Tree store 3040 at 1524 E. Joppa Rd. in Baltimore Maryland the following incident of extremely poor customer service occurred.
At approximately 2:30 p.m. I got in line behind 5 other customers and eventually 5 others behind me for the one cashier that was open. Another employee who was later identified as Jacob Tew was assisting a customer with balloons. He then went to another cash register, rung up the customer with the balloons, but did not turn on the light to indicate that the line was open, nor did he notify the other customers he was open. I advised him that what he did was very poor customer service and was very inappropriate. He stated to me that it was the customer's discretion as to what line they went to and what I thought was my opinion. His attitude was very matter of fact, rude, arrogant, condescending and totally unapologetic for his actions. I have never experienced this type of behavior in one of the Dollar Tree stores. Please address. Thank you.