The Android app only unlocks with a fingerprint even if the ability to unlock with face ID is present.
As noted here this is a known limitation in the Android implementation:
For Android we support only two states: None (default) and Fingerprint (use only biometric protected storage); Face recognition fails with "User not authenticated" exception, see issue #318
To fix this issue we would need to fix 318 in the underlying package we use. Read the conversation, someone did submit a PR to fix but it was never merged.
The Android app only unlocks with a fingerprint even if the ability to unlock with face ID is present.
As noted here this is a known limitation in the Android implementation: