I tried to donate to my local blood bank post-transition a few years ago. The blood bank refused to let me donate blood as a man until I have bottom surgery. I obviously don't have an inside track on their logic, but I can't see any earthly reason for this refusal to properly classify me. I agreed to donate anyway because I was already there and had gone to considerable trouble to donate. But I started disconnecting, and I had a meltdown afterward. Consequently, I won't be donating again.
The blood bank is thus missing out on my donation of one of the less common blood types, although, of course, there's always type O if there's a shortage.
I was told that the blood bank was following Red Cross guidelines. But I understand that plasma collection centers have their own rules.