How to remove tint on icon in Material Button?

You can also use white color as iconTint and use multiply as iconTintMode for colorful icons.

 app:iconTint="@color/white"
 app:iconTintMode="multiply"

Use this and quit tint icon to show real color

  app:icon="@drawable/ic_google"
  app:iconTint="@null"

Example

<Button
  android:id="@+id/idGoogle"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  app:icon="@drawable/ic_google"
  app:iconTint="@null"/>

icon with real color shows black background

I already found a solution, I just changed iconTintMode and iconTint color

  <android.support.design.button.MaterialButton
    style="@style/Widget.MaterialComponents.Button.Icon"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Sign in with Google"
    app:icon="@drawable/ic_google_colored"
    app:iconTint="@android:color/transparent"
    app:iconTintMode="add"/>

I am open to better solutions