You can always complain [to Revolut], or you can find an alternative.
Or both, perhaps?
I just wrote to Revolut customer support, explaining that the newest app version appears to block GrapheneOS*, briefly explained about its security and privacy features and why I use it, and that I'll be locked out of the Revolut app soon and will therefore close my account if GrapheneOS is not allowed to run the app. I also linked to the attestation guide as a way for the developers to allowlist GrapheneOS, and kindly asked that my feedback be forwarded to the development team.
The support agent replied:
I understand your concern about the Revolut app blocking new sign-in attempts on GrapheneOS, despite it working previously. Revolut does not officially conduct compatibility tests or provide official app functionality on GrapheneOS or other custom Android-based operating systems. The message you received indicates that Revolut is serious about data security and currently requires the use of devices with official Android firmware for app access.
Quite a predictable reply from a CSR. But also:
I have shared your feedback with our Developments team for the betterment in future.
which is at least something. Let's see if they change anything.
I encourage everyone who's a customer to write to Revolut and complain about this. Let's try to put some pressure on them. As long as you haven't signed out of the app, you'll be able to open a ticket.
I've also left a one-star review with a brief explanation on their Play Store entry. Think that's entirely fair.
*I know that it's likely not blocking GrapheneOS specifically, but more likely blocking all OSs that are not stamped with Google's certification, but it seemed too much to go into details on that in a support chat. Think it was clear that I don't care about those OSs anyway.