The text button will take on a background based on the app's primary colour, but the ImageButton has a grey background.
From various web and AI searches, I have tried the following, but they either do nothing, cause the button to disappear, or the layout inflation fails:
android:background="?android:attr/selectableItemBackground"
and
style="?android:attr/buttonStyle"
and
android:background="?android:attr/buttonStyle"
<ImageButton
android:id="@+id/btn_take_picture"
android:background="?android:attr/selectableItemBackground"
android:layout_width="110dp"
android:layout_height="wrap_content"
android:layout_marginBottom="50dp"
android:layout_marginEnd="50dp"
android:elevation="2dp"
android:text="Photo"
android:src="@drawable/ic_menu_camera"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintEnd_toStartOf="@id/vertical_centerline" />
<Button
android:id="@+id/btn_record_video"
android:layout_width="110dp"
android:layout_height="wrap_content"
android:layout_marginBottom="50dp"
android:layout_marginStart="50dp"
android:elevation="2dp"
android:text="Record"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="@id/vertical_centerline" />
Quite why this isn't done as standard, I don't know.