Android ProgressBar background color gets gray when parent layout's background is light

Tried many solutions but didn't work for this problem

Problem:
I have a progress bar in my Android app, and I've applied a custom style to it that makes it horizontal and changes its background and progress color. However, when I set a light color as the background of the parent layout, the progress bar's background color gets a gray shade instead of the original color I specified in the style.

Pic 1 (Expected Behavior): When I set a dark color as the background to the parent layout

Color used:

<color name="colorYellow">#E2DA85</color>

Pic 2 (Actual Behavior): When I set milk or any light shade color as the background to the parent layout

Color used:

<color name="colorMilk">#FDFDF5</color>

Here is my activity layout file:

<?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:background="@color/colorYellow"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ProgressBar
        android:id="@+id/progressBook"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginHorizontal="20dp"
        android:layout_marginTop="100dp"
        android:progress="75"
        style="@style/CustomProgressBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Please note

> android:background="@color/colorYellow"

And here is the custom style for progressbar named CustomProgressBar:

<style name="CustomProgressBar" parent="android:Widget.ProgressBar.Horizontal">
    <item name="android:indeterminateOnly">false</item>
    <item name="android:progressDrawable">@drawable/progressbar_book</item>
    <item name="android:minHeight">10dip</item>
    <item name="android:maxHeight">20dip</item>
</style>

And here is the custom drawable file named progressbar_book that I made for the progressbar:

<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/background">
        <shape>
            <corners android:radius="10dp" />
            <gradient
                android:startColor="@color/colorCotton"
                android:centerColor="@color/colorCotton"
                android:centerY="0.50"
                android:endColor="@color/colorCotton"
                android:angle="270" />
        </shape>
    </item>
    <item android:id="@android:id/progress">
        <clip>
            <shape>
                <corners android:radius="10dp" />
                <gradient
                    android:startColor="@color/colorViolet"
                    android:endColor="@color/colorViolet"
                    android:angle="90" />
            </shape>
        </clip>
    </item>
</layer-list>

colorCotton:

<color name="colorCotton">#F2F6EE</color>

How can I get the progressbar to show the correct background color even when the parent layout has a light color background?

It seems there is no issue with your code. Your colorCotton colour may have a little bit grey. since you didn't mention the colour code I replaced it with your ColorMilk and its works perfectly fine.

Pic 1: Both background and Progressbar gradient colour as ColorMilk

Pic 2: Background as colorYellow

I used #7F1419 as progress color