Question about play services

Hello! I'm running GrapheneOS on my Pixel 7 with sandboxed play services, and use some apps that depends on play services like Satispay and my banking app. Today I tried, as an experiment, to deactivate the play service app, and see what happens. Well, they both opens and seem to work, except for a notification saying "Activate Play Services, this app will not work if you don't" Is this notification lying? Or are some functionalitis not working without play services? If yes, which one?