Dark mode list preference not working. Is dark for a second and then is light

Question

I added adaptive themes in my application using List Preferences and it does not work. Sometimes when I create Build APK and test Preferences, the theme it sets to dark for a second and returns to the light one... I do not understand why it does so. Am I missing something..?

I added an activity for settings:

class SettingsActivity : AppCompatActivity(), SharedPreferences.OnSharedPreferenceChangeListener {
    private lateinit var binding: SettingsActivityBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = SettingsActivityBinding.inflate(layoutInflater)
        setContentView(binding.root)
        supportFragmentManager.beginTransaction().replace(R.id.settings, SettingsFragment()).commit()
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(this)
    }
    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
        val darkModeString = getString(R.string.dark_mode)
        key?.let {
            if (it == darkModeString) sharedPreferences?.let { pref -> val darkModeValues = resources.getStringArray(R.array.dark_mode_values)
                when (pref.getString(darkModeString, darkModeValues[0])) {
                    darkModeValues[0] -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
                    darkModeValues[1] -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
                    darkModeValues[2] -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)
                    darkModeValues[3] -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_AUTO_BATTERY)
                }
            }
        }
    }
    class SettingsFragment : PreferenceFragmentCompat() {
        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
            setPreferencesFromResource(R.xml.settings_preferences, rootKey)
        }
    }
}

Also the arrays:

<resources>
    <string-array name="dark_mode_entries">
        <item>Follow System</item>
        <item>Light Mode</item>
        <item>Dark Mode</item>
        <item>Auto Battery Dark Mode</item>
    </string-array>
    <string-array name="dark_mode_values">
        <item>MODE_NIGHT_FOLLOW_SYSTEM</item>
        <item>MODE_NIGHT_NO</item>
        <item>MODE_NIGHT_YES</item>
        <item>MODE_NIGHT_AUTO_BATTERY</item>
    </string-array>
</resources>

And the Preference:

        <androidx.preference.ListPreference
            app:defaultValue="@string/theme_def_value"
            app:entries="@array/dark_mode_entries"
            app:entryValues="@array/dark_mode_values"
            android:icon="@drawable/ic_settings_themes"
            app:key="@string/theme"
            app:title="@string/theme"
            app:useSimpleSummaryProvider="true"/>

What is missing? I can't figure out why it turns dark for a second and then it comes back to light theme....

I used this dark mode tutorial to add it in my app....