LibreTube/app/src/main/res/drawable/ic_play.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:tint="?attr/colorControlNormal"
    android:viewportWidth="24"
    android:viewportHeight="24">
    <path
        android:fillColor="@android:color/white"
        android:pathData="M8,5v14l11,-7z" />
</vector>