Banking apps are a complex story, really.
As a current example, look at https://community.e.foundation/t/securego-plus-app-stopped-working/75832. It has some tables that includes the bootloader lock state, but it doesn’t seem to be the real factor.
All depends on your precise needs. And it’s of course up to you.
For example for me “being able to recover by installing a different recovery and debugging from there” is more important then 105% working banking apps. Just my 2 cent.