Method 1: Blocking Phone notification using third party app
Before you do this, check if your Android device has a built-in feature to disable notifications. This feature may be available in Android 5.0 Lollipop and Android 6.0 Marshmallow operating systems, but some systems may not give access to the “phone” app. Go to settings >> sounds and notifications >> Apps >> Scroll down and tap on “Phone” and disable notification. If your phone doesn’t have that feature, it’s time to give some third party apps a try.
If you Android phone is rooted, there is a fix. You can download apps that can block “Restricted access changed” notification.
Download Notification blocker app like this one: Notify Block
Open the app >> You will be asked to grant notification access >> Tap “OK”
Now on the app uncheck “Hide System Apps”
Scroll down and tap on “Phone” (com.android.phone)
Now reboot device and see if the error still persists. Within the notify blocker app, you may find several “Phone” icons. If the above steps didn’t work, try disabling notifications for each of the “Phone” icons on the list.