Reading through your post it sounds like you have the app up and running but it refuses to unlock using the biometric of facial recognition, is this correct?
How long have you had the app? How long have you had the phone? Are either of these new to you?
If neither is new to you, has facial recognition ever worked for you on this device for any app or for unlocking the device?
Does everything else with the app work?
This all sounds like 2020 I think it was, when Samsung had a security issue with the fingerprint reader on one of it's devices. When this issue was exposed many of the banking apps I had stopped working with the fingerprint reader and these bans were specific to my device. Fingerprint continued to work for other devices and I still had the option to enable it but each time I would attempt to I would either get a failed, or it would act like I had succeeded but then would not work. This was also around the same time there was a big push from Google that banking and other apps with biometric security start accepting facial recognition in addition to fingerprint or in lieu of fingerprints. I heard this was due to more devices having cameras than fingerprint scanners. Anyway I'm wondering if the app may have disabled this feature for this device. Perhaps the hardware is not sufficient enough to support a high enough security protocol needed for the banking app to feel secure. You might try contacting the app developer to see if they can confirm this or help with tips on how to get facial recognition working. Honestly they should be better equipped to offer you assistance than we are.
Let us know what you find out.