Do not request access to sensitive personal information such as "full date of birth" just to allow sign in to another account.
Asking for sensitive identity info makes the app look like it is phishing. My bank makes it a virtue never to ask for anything like that and teaches me to mistrust those who do. Two factor authentication should not need access to my date of birth or similar. Any information used should be encrypted and disposable in case of account or server compromise. I can change my password but not my date of birth.