Hi foresty, If Fingerprint always-on feature is enabled, the device will be woken and scan fingerprint whenever Side key is touched.
Accordingly, please deactivate Fingerprint always-on feature to avoid accidental fingerprint scans on the following path.
Also, be sure to not be touched Side key by fingerprint unintentionally while the screen turns on.
Settings > Biometrics and security > Fingerprints > Swipe to deactivate Fingerprint always-on feature.
Also, set the device to prevent the screen from detecting touch input when it is in a dark place, such as a pocket or bag by enabling "Accidental touch protection".
Please perform the wipe cache partition and check if the issue is resolved.