While on loan Mitrita does not use a DP slot. Young DPs do use DP slots, so Talles, as a young DP, counts. Medina was a young DP for most and maybe all of his time here. I forget if he was still officially "young" at the end. Mitri comes off loan this summer and his NYCFC contract runs to the end of the 2022 season. So this summer we either have to transfer him, make a half-season loan, or convert one of our 3 DPs with TAM to be compliant. The plan is to resolve Mitrita and still buy down someone with TAM, probably Martins, which would open up a new slot to fill.
I believe the consensus is that we could have signed Martins on a TAM deal to start, but for our owner, TAM is a bigger constraint than DP spending, so we make him a half-season DP and conserve TAM until we need it.