What's this strange white rectangle behind my toolbar?

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;
  }
  });

It is the shadow of the AppBarLayout. Use:

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