Based on previous questions, the Galaxy A34 uses an optical fingerprint sensor, this is an entirely separate sensor from the display, your biometrics should be safe, unless the app is actively trying to steal it from memory. On Samsung's flagship phones, they store the biometric data in something called "Knox Vault", which is basically a super secure chip which no 3rd party application can access. Other Samsung phone's don't have this and store sensitive data in "normal" storage.
