Replying to
@GrapheneOS @adfichter Just in case it helps anyone, I quickly tested it with secure app spawning disabled and compat mode on but the issue @adfichter describes persists. These are the official OS requirements for the app: https://help.agov.ch/?c=myphone&l=en
It says installation exclusively from Play Store. I installed it from aurora store, so could it be a Play integrity issue in my case?