Santander bank app fails to work unless 'Secure app spawning' is disabled

We've seen apps doing this a few times before and have an idea of why it's happening. It's incredibly rare and caused by a misguided and broken attempt at anti-tampering. It will also likely break in future Android releases and with certain OEM variants of Android. They're likely using some debugging functionality to check the initial call stack and are hard-wiring specific permitted call stacks. Secure spawning has a slightly different initial call stack from how it starts differently. It's possible we can make it align or at least fake it so these apps stop banning GrapheneOS when secure spawning is enabled.