The a13 is part of samsungs budget phone line-up. The A series isn't focused on flagship specs. You knew what you were getting when you got an A13. And if you didnt, try and do more research next time.
Like Jacobbbb said, it is an affordable phone, meaning it has lower end cameras. My A11 is not an exceptional camera by any means. The A1X (A11, A12, A13, etc.) lineup is very budget friendly, so if you want good cameras I suggest getting an S series or Note.