calyceal diverticulum and hydronephrosis, no stones

Hi everyone, I had a pyleoplasty/upj surgery done on my right kidney in June 2022. I had a kinked ureter, a vein wrapped around my kidney, and my kidney was malrotated. My hydronephrosis was fully gone after surgery. It has been two years and it is fully back and moderate. I recently had a mri done and it said I had upper pole calyceal diverticulum. Does anyone know what this is and the treatment? Everything I have read says they remove stones to treat calyceal diverticulum, but I do not have stones.