Uninstall harmful app' notification for my own app

Question

I am developing an app with Kotlin on Android.

The app is not published to Google Play yet.

As it is getting close to being finished, I am trying it on various devices. I have developed it with minSdk 28, however I got a hold of an API level 27 device so I changed my build.gradle to 27 for minSdk and deployed my app.

After I used my app for a bit, I got a 'uninstall harmful app' notification from Google Protect.

However, when I tapped on it, there were no details and 'No threats detected'. I tapped Scan now and my app appeared in the list of recently scanned apps and no more threats were reported.

I have been debugging on API 30 device and have never seen anything like this there.

Is there any way to find out why Google Play Protect flagged my app before I submit it to review?

Update

My app's features and permissions:

<!-- Features -->
    <uses-feature
        android:name="android.hardware.camera.any"
        android:required="true" />

    <!-- Permissions -->
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission
        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="28" />