If you want to use multiple options pages for plugin, ensure that your sanitize function gets the additional missing options from the database
example
public function sanitize($input): array
{
/** My Plugin Setting Options */
$option = get_option('my_plugin_settings');
/** Do this for all the settings keys in your options array */
if ($input['setting_key']) {
$output['setting_key'] = $input['setting_key'];
} else {
$output['setting_key'] = $option['setting_key'];
}
return $output;
}