Camera2 API compatibility issues with google play store

I have developed an android app that uses the camera2 API. I am able to run this app on my own physical device when I'm debugging, but when I try to publish the app to the google play store, it says that my device isn't compatible - in fact, no devices are compatible with my app.

I have been in contact with google support, and they said that "your app is not compatible with most devices due to a conflict in your app’s manifest because of the following missing device feature: android.hardware.camera2. "

I have noticed that the min-sdk version in my gradle file was set to 15.
So my question is: Will my app become compatible with my devices if I change the min-sdk version to 21, or do I need to rewrite my entire code to use the deprecated camera API instead?

Thanks in advance.

*Edit:
This is my android manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="...">
<uses-feature
    android:name="android.hardware.camera2"
    android:required="true"/>

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:name=".app.AppController"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <meta-data
        android:name="com.google.android.gms.vision.DEPENDENCIES"
        android:value="barcode"/>

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar"
        android:screenOrientation="portrait">

    </activity>

    <activity
        android:name=".ResultsActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar"
        android:screenOrientation="portrait">

    </activity>

    <activity
        android:name=".QRScanner"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>