Bank backend is needed for security and monitoring reasons. Bank mobile apps are usually using a token (e.g. JWT) linked to individual client.
This token should not be exposed to a 3rd party, since it could be theoretically exploited to act on client behalf.
Dateio and Bank also need a common X-client-id to identify the client across API calls, cards linked to client, transactions,
and cashback payout. Dateio is not able to extract this client id from the bank mobile app token. Also, bank might want to monitor traffic or requests
that SDK perform.
You can find more informations about Bank backend in this section.>