android uses centred app icon in launch screen instead of the image in launch_background

Question

EDIT: Solution: https://stackoverflow.com/a/71396586/18197688

If I change the app icon (ic_launcher.png) then it will be shown at splash screen, but also the app icon changes.

It feels as if there were some hidden setting that centers the icon at the splash screen. Background color changing works.

Using io.flutter.embedding.android.SplashScreenDrawable also works but I understand it is discouraged.

My launch_background.xml

    <?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <bitmap android:gravity="fill" android:src="@drawable/background"/>
    </item>
</layer-list>

My launch_background.xml in drawable-v21

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <bitmap android:gravity="fill" android:src="@drawable/background"/>
    </item>
</layer-list>

My android manifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.my_app">
    <uses-permission android:name="android.permission.INTERNET" />
   <application
        android:label="my_app"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:theme="@style/LaunchTheme"
            android:exported="true"
            android:launchMode="singleTop"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
    
</manifest>