I am working on a music app in kotlin, I have a problem, after I set a transparent background in themes for the action bar, the action bar has some borders. How can I remove them? I will be grateful for any help

Code:

action_bar.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:id="@+id/actionBar"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appBarLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?actionBarSize"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent">

                <androidx.constraintlayout.widget.ConstraintLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">

                    <ImageButton
                        android:id="@+id/buttonBack"
                        android:layout_width="wrap_content"
                        android:layout_height="0dp"
                        android:background="@android:color/transparent"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintHorizontal_bias="0.0"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toTopOf="parent"
                        app:srcCompat="@drawable/ic_back" />

                    <TextView
                        android:id="@+id/appTitle"
                        android:layout_width="wrap_content"
                        android:layout_height="0dp"
                        android:layout_marginLeft="32dp"
                        android:gravity="center"
                        android:text="@string/app_name"
                        android:textColor="@color/white"
                        android:textSize="27sp"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintStart_toEndOf="@+id/buttonBack"
                        app:layout_constraintTop_toTopOf="parent" />

                    <ImageButton
                        android:id="@+id/songListButton"
                        android:layout_width="wrap_content"
                        android:layout_height="0dp"
                        android:layout_marginEnd="16dp"
                        android:background="@android:color/transparent"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintTop_toTopOf="parent"
                        app:srcCompat="@drawable/ic_music" />
                </androidx.constraintlayout.widget.ConstraintLayout>

            </androidx.appcompat.widget.Toolbar>

        </androidx.constraintlayout.widget.ConstraintLayout>

    </com.google.android.material.appbar.AppBarLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

I don’t even have any idea why this could be… I checked the code, I haven’t set the borders for the action bar before