If a user is subscribed to Push API (not the old Apple only push notifications), but then blocks notifications in safari settings or system preferences, the endpoint is still valid. The response from the server that sends the push notification should be 40* if the subscription is no longer valid. this allows the server to remove that subscription However on safari it is always valid, causing a build up of expired/unused subscription endpoints which must still be called in case they are valid. To re-create: subscribe to user notifications in safari settings, set to the domain's notification settings to deny trigger push notification on server. it's response will still be 200 even though the subscription is now invalid