优化

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -2,4 +2,5 @@
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
     <background android:drawable="@drawable/ic_launcher1_b" />
     <foreground android:drawable="@drawable/ic_launcher1" />
+    <monochrome android:drawable="@drawable/ic_launcher4" />
 </adaptive-icon>

app/src/main/res/mipmap-anydpi-v26/launcher4.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@color/md_grey_50" />
+    <background android:drawable="@drawable/ic_launcher4_b" />
     <foreground android:drawable="@drawable/ic_launcher4" />
 </adaptive-icon>