It might involve the Google Play Integrity API. GrapheneOS officially passes only the MEETS_BASIC_INTEGRITY tier of the Google Play Integrity API and fails the

It might involve the Google Play Integrity API. GrapheneOS officially passes only the MEETS_BASIC_INTEGRITY tier of the Google Play Integrity API and fails the MEETS_DEVICE_INTEGRITY and MEETS_STRONG_INTEGRITY levels. Many banking apps I use in my country require this level plus something from the GPI API, which makes them unusable. You need a regular, unmodified smartphone to use them.