Why add issuer option(mobile wallet) returns diferents pubkey each time

hi this is my profile https://6073a6b0e4e0160017ddfc72.mockapi.io/profile

and my introduction url is https://6073a6b0e4e0160017ddfc72.mockapi.io/recipient
you can (get) also this endpoint to see what i mean

and each time i add an issuer it (post) returns me a different bitcoinAddress value with the same blockcert wallet , why is that way , as i understand the pubkey is always the same , can someone explain it please