Purchase cancelled on hardware back button hit from bank verification redirect

Hello, 

this is all about Android, iOS works fine.

The title sums it all basically. Little code environment context - I do launch a new activity upon purchase under singleTop launchmode. So it’s separated from my singleTask Main Activity.

Now the issue. When user gets a bank redirect to verify payment, it all goes well, everything works, they confirm. But once they go back via the hardware button, the purchase gets cancelled. If they background the bank verification and bring my app forward, it all works as expected. What should about it? Thank you.
 

<activity
            android:name=".PurchaseActivity"
            android:theme="@style/AppTheme"
            android:launchMode="singleTop"
            android:taskAffinity="cz.erudita.app"
            android:excludeFromRecents="true"
            android:alwaysRetainTaskState="true"
            android:clearTaskOnLaunch="false"
            android:windowSoftInputMode="adjustResize"
            android:screenOrientation="portrait"
            android:exported="true">

            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT"/>
                <category android:name="android.intent.category.BROWSABLE"/>
                <data android:scheme="cz.erudita.app" android:host="objednavka" />
            </intent-filter>
        </activity>