Why is my iOS Development Certificate Team ID different from my real Team ID?
I've since had communication with the Apple Developer Program Support and they've sent me an email clarifying the team IDs.
This is what they wrote:


  Please note that I can confirm that the ID assigned to the IOS Development Certificate is a random one and is not the Team ID, therefore it is expected behavior. The ID assigned to the IOS Distribution Certificate would match the TID.


It seems the TeamID of the Development Certificate is in fact random. I wasn't able to do purchases in my app because of a bug and not this error.