OP still has not confirmed what the redemption was for, but I would assume it was a points transfer.

My own experience, as a Prestige Card holder and who has a Citi checking account that used to earn TY points, is consistent with the guidance mia has posted.

To use expiring points (which were all earned via my checking account), I had to redeem for statement credits, gift cards, etc. Those redemptions always resulted in the expiring points being pulled first.

The way you can tell that points previously earned via banking cannot be transferred to airlines/hotels is that when you try to transfer online, the balance for points eligible for transfer will always be less those points.