Is there any way to tell Flask to ignore a path?
By the time Flask is handling a request, the web server has already passed the request to the application and is awaiting a response. At that point, there's no protocol for Flask to "cancel" handling the request. You'll need to modify Apache's configuration to only pass requests which do not match your path to the Flask application. If you're on a shared host, you might still be able to modify an .htaccess file to set up the forwarding rules.