Order tab on other user page is visible but the page is not accessible

I spent all day fixing this. The best way is unclear, but I had to create a custom Access class like this:

class IsMyUserOrAdmin implements AccessInterface {
  protected $routeMatch;
  public function __construct(RouteMatchInterface $route_match) {
    $this->routeMatch = $route_match;
  }

  public function access(AccountInterface $account) {
    // return true if the useris an admin or the user id in the route matches the current user id
    return AccessResult::allowedIf($account->hasPermission('administer users')
      || $account->id() == $this->routeMatch->getParameter('user')->id());
  }
} 

Then set it up as a service like:

  mymodule.is_my_user_or_admin:
    class: Drupal\mymodule\Access\IsMyUserOrAdmin
    arguments: ['@current_route_match']
    tags:
      - { name: access_check, applies_to: _mymodule_is_my_user_or_admin }

Then since this is a view, I made it a views custom access plugin, with this being the operative part.

  public function alterRouteDefinition(Route $route) {
    $route->setRequirement('_custom_access', 'mymodule.is_my_user_or_admin::access');
  }

I am kind of blown away by how much knowledge and engineering was needed to solve this very simple problem. There is perhaps an easier way but this was the most functional way, that can be reused in the system in similar cases.

Stumbled across this behavior, and did a bit of issue digging. I appreciate the code example that you posted as that'll help me.

It looks like this has been an issue with Views since Drupal 6 and Drupal 7 in contrib., and carried over into Views in core in Drupal 8, 9, 10 and 11 #426114: Option to prevent view access (eg to hide tab) when view is empty

I tried this code to put the class "my-profile" into the body, but it breaks the site when clicking on "Orders" (Commerce) tab.

function MYTHEME_preprocess_page(array &$variables) {
  $current_user = \Drupal::currentUser();  
  if ($user = \Drupal::routeMatch()->getParameter('user')) {
    if ($user->id() == $current_user->id()) {
      $variables['attributes']['class'][] = 'my-profile';
    }
  }
}