What's this strange white rectangle behind my toolbar?

Question

I've been trying to get rid of it all day to no avail. Tried giving every view and layout around it an invisible background color. Also tried reducing the size of the layouts and views it's in. Those sharp white edges persist. What are they? Also hi this is text filler, website says there's too much code and too little text. "Hi text filler, you good?"

• activity_main.xml:

  <?xml version="1.0" encoding="utf-8"?>
  <androidx.constraintlayout.widget.ConstraintLayout 
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".MainActivity">
  <include
      android:id="@+id/mainToolbar"
      layout="@layout/toolbar"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent" />
  
  <androidx.coordinatorlayout.widget.CoordinatorLayout
      android:layout_width="0dp"
      android:layout_height="0dp"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/mainToolbar">
  
      <com.google.android.material.appbar.AppBarLayout
          android:id="@+id/tab_anim_appbar"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_gravity="center|top"
          android:layout_marginLeft="20dp"
          android:layout_marginRight="20dp"
          android:background="#00FFFFFF">
  
          <com.google.android.material.appbar.MaterialToolbar
              android:id="@+id/searchToolbar"
              style="@style/Widget.MaterialComponents.Toolbar.Primary"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_gravity="center|top"
              android:background="#A106A1"
              android:elevation="2dp"
              app:contentInsetLeft="0dp"
              app:contentInsetStart="0dp"
              app:layout_scrollFlags="scroll|enterAlways">
  
              <!-- dummy to catch focus -->
              <LinearLayout
                  android:layout_width="0px"
                  android:layout_height="0px"
                  android:focusable="true"
                  android:focusableInTouchMode="true" />
  
              <androidx.appcompat.widget.SearchView
                  android:id="@+id/searchView"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"
                  android:animateLayoutChanges="true"
                  android:layoutDirection="rtl"
                  app:iconifiedByDefault="true"
                  android:layout_marginLeft="30dp"
                  android:layout_marginRight="30dp"/>
  
          </com.google.android.material.appbar.MaterialToolbar>
  
      </com.google.android.material.appbar.AppBarLayout>
  
      <include layout="@layout/content_scrolling"/>
  
  </androidx.coordinatorlayout.widget.CoordinatorLayout>
  
  </androidx.constraintlayout.widget.ConstraintLayout>
  

• The toolbar in code:

      //code to make the toolbar edges round
      MaterialToolbar searchToolbar = findViewById(R.id.searchToolbar);
      MaterialShapeDrawable searchbarBackground = (MaterialShapeDrawable) searchToolbar.getBackground();
      searchbarBackground.setShapeAppearanceModel(
              searchbarBackground.getShapeAppearanceModel()
                      .toBuilder()
                      .setBottomRightCorner(CornerFamily.ROUNDED,100)
                      .setBottomLeftCorner(CornerFamily.ROUNDED,100)
                      .build()
      );
  
      //code to add search function
      SearchView searchView = findViewById(R.id.searchView);
      searchView.setImeOptions(EditorInfo.IME_ACTION_DONE);//so that button on keyboard is a check
      searchView.setQueryHint("Search...");
      searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
          @Override
          public boolean onQueryTextSubmit(String query) {
              return false;
          }
  
          @Override
          public boolean onQueryTextChange(String newText) {
              ItemAdapter.getFilter().filter(newText);
              return false;
          }
      });
  

Answer 1

It is the shadow of the AppBarLayout. Use:

<com.google.android.material.appbar.AppBarLayout
    app:elevation="0dp"
    android:background="@android:color/transparent"