This happened to me with Starling Bank's app years ago. I have since conceded defeat. What is pernicious is how some of these services are unusable without an app, while also bossing the user around about what operating system they can use. Starling left me without any access to any of my bank accounts at the time (2022 or so) so now I use very old school online banking now to avoid this situation ever occurring again.
It's because PayPal shipped an update with incorrect anti-tampering code incompatible with secure app spawning. It can be worked around with the per-app secure app spawning toggle until they fix it.
Starling Bank app still works on GrapheneOS too. See here:
