#access permissions

Is this the same issue as:
https://www.drupal.org/project/nodeaccess/issues/3509391 💬 Upgrade to version 2 deletes existing permissions Active

If so we should also mark one of these as closed (duplicate).

nodeaccess.settings.yml 1.x

grants:
  view: 1
  edit: 1
  delete: 1
priority: 0
preserve: 1

nodeaccess.settings.yml 2.x

allowed_grant_operations:
  grant_view: true
  grant_update: true
  grant_delete: true
bundles_roles_grants: {}
grants_tab_availability: {}
map_rid_gid: {}
roles_settings: {}

There is an update hook provided in nodeaccess.install:
https://git.drupalcode.org/project/nodeaccess/-/blob/2.0.x/nodeaccess.in...

/**
 * Migrates nodeaccess.settings.
 */
function nodeaccess_update_9002(&$sandbox) {
  $config = \Drupal::configFactory()->getEditable('nodeaccess.settings');
  // From grants to allowed_grant_operations.
  $old_grants = $config->get('grants');
  $config
    ->set('allowed_grant_operations', [
      'grant_view' => (boolean) $old_grants['view'],
      'grant_update' => (boolean) $old_grants['edit'],
      'grant_delete' => (boolean) $old_grants['delete'],
    ])
    ->clear('grants');

  // From allowed_types to grants_tab_availability.
  $old_allowed_types = $config->get('allowed_types') ?? [];
  $grants_tab_availability = [];
  foreach ($old_allowed_types as $bundle => $value) {
    $grants_tab_availability[$bundle] = (boolean) $value;
  }
  $config
    ->set('grants_tab_availability', $grants_tab_availability)
    ->clear('allowed_types');

  // From role_map to map_rid_gid.
  $old_role_map = $config->get('role_map');
  $config
    ->set('map_rid_gid', $old_role_map)
    ->clear('role_map');

  // From role_alias to roles_settings.
  $old_role_alias = $config->get('role_alias');
  $roles_settings = [];
  foreach ($old_role_alias as $role_id => $value) {
    $roles_settings[$role_id] = [
      'display_name' => $value['alias'],
      'name' => $value['name'],
      'weight' => (int) $value['weight'],
      'selected' => (boolean) $value['allow'],
    ];
  }
  $config
    ->set('roles_settings', $roles_settings)
    ->clear('role_alias');

  $bundles = array_keys($old_allowed_types);
  $bundles_roles_grants = [];
  foreach ($bundles as $bundle) {
    $old_bundle_settings = $config->get($bundle);
    foreach ($old_bundle_settings as $role_id => $grant) {
      $bundles_roles_grants[$bundle][$role_id] = [
        'grant_view' => (int) $grant['grant_view'],
        'grant_update' => (int) $grant['grant_update'],
        'grant_delete' => (int) $grant['grant_delete'],
      ];
    }
    $config->clear($bundle);
  }
  $config
    ->set('bundles_roles_grants', $bundles_roles_grants)
    ->clear('priority')
    ->clear('preserve')
    ->save();

}

Did you run drush updb / drush updatedb and drush cr / drush cache:rebuild?

Please let me know and I can investigate this further if you're still having issues?