TPMS discrepancy

Hello friends,

I have a 2019 Chevrolet Traverse that's been having a slow leak with the left rear tire for the past year. I should have taken it into the shop, I know but it only needed 10 PSI every couple of weeks so it was always a back burner issue. I just had the tires rotated, idk if the back left tire went to front left or front right. I've been waiting for the TPMS to come on and tell me what side it's on now, but when it did it's still the the left rear tire that's losing air. I know they were rotated because the tread ware was different after the rotation, so I know for a fact the tire moved. It doesn't make sense to me that a tire losing air, when rotated suddenly holds air and the position on the car is what determines how it holds pressure. What's wrong with my car?