after minimize the app from singleInstance launchMode activity, all previous activities in backStack destroyed

Question

I am running into issue where onDestroy() invoked for all previous activities when singleInstance activity is running and i minimize my app.

i create a sample App to check this behavior:

my Manifest

        <activity
            android:name=".MainActivity3"
            android:launchMode="singleInstance"
            android:exported="false">
            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
        <activity
            android:name=".MainActivity2"
            android:exported="false">
            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>

and this is whats happend:

I navigate to activity3 by intent:

activity1 -> activity2 -> to activity3 (this launchMode:singleInstance)

and the problem now is when i minimize my app when the singleInstance activity visible -> all activities in stack was destroyed.

and this is the logcat:

D/Hofit: MainActivity1 - onResume
D/Hofit: MainActivity2 - onResume
D/Hofit: MainActivity3 - onResume
D/Hofit: MainActivity2 - onStop
D/Hofit: MainActivity1 - onStop
//activity3 visible and i minimimize
D/Hofit: MainActivity2 - onDestroy
D/Hofit: MainActivity1 - onDestroy
D/Hofit: MainActivity3 - onStop

why this is happend in my app and sample when app gose to background? how can i solve this? why activities destroyed and not just stop?

Thanks!