Thank you for your review!
The cleanup should happen automatically, the expired subscriptions will be removed once your next notification is sent (basically, the plugin tries to send a notification and it removes the subscription if it fails).
So, it won’t happen as soon as a user unsubscribes, but will happen eventually.
I’m thinking about adding custom push notifications (https://github.com/mozilla/wp-web-push/issues/195). Your input on how you would like to see the statistics for this kind of notification would be useful (a single notification clicked/notification opened number for all custom notifications or multiple numbers, one for each custom notification).
What do you mean by “combined notifications for new post and post update”?
The plugin is on GitHub, you can file issues there: https://github.com/mozilla/wp-web-push/issues.
