u/D3lta0kami

Hi all!
I have been using an s25 ultra I bought off back market for a bit now and all of a sudden it seems to be carrier locked again? I picked it up and unlocked it and suddenly it's telling me it's locked and my SIM won't work with it.
I am opening a case with backmarket as it hasn't been that long since purchase.

update: I have since found that the phone still has an outstanding balance on it according to T-Mobile. This implies that the phone was not unlocked through normal means.