Are you using a VPN? Are play services still running or did you disable it after installing the apps?
Have you tried toggling the Exploit protection compatibility mode in the app info setting for each app as well as other requested permissions? Most banking apps work, but they sometimes require extra permissions and don't play well with some of GrapheneOS's default security protections. This is why many people choose to install them on a separate profiles to better isolate them.
Also,just so you're aware, depending on what you're using the apps for, much of the same functionality should be available by logging in via the browser. Mobile depositing checks has so far been the only thing I needed a banking app for and I haven't had to do that in years. ATMs and local branches also still exist for this purpose.