Hi calamityadam! 👋

• Subscriptions aren’t new, exactly, they’re just giving you visibility into the places that you’re already set up to get notifications from.
• There are a bunch of ways that you could be set up to receive notifications about a repo or PR that don’t involve you manually subscribing yourself, such as being assigned to a PR, being @mentioned, etc. More details can be found here.
• There is a setting that automatically sets you to watch repositories as you gain access to them. You can read about disabling it here. That wouldn’t stop you being subscribed to things you are @mentioned in or assigned to, though. It is possible to “ignore” a repository when unwatching it so that you wouldn’t receive notifications when @mentioned or assigned to issues or PRs, but obviously you need to be very certain that missing those notifications won’t cause you problems.
• The subscriptions page allows you to sort by the date the subscription started, so you can potentially more easily review old and out of date subscriptions, or only your most recent ones. It also shows source of notifications that won’t show up in the notifications view if you have marked them “done”. More details here.
• Unsubscribing from absolutely everything isn’t possible through the web UI, sorry! You could perhaps use the API to do things faster than 25 at a time, though.

Bonus - I suspect this is about performance - if we tried to load all of your subscriptions through the web UI in one go it would likely time out and cause problems.

Sorry that these aren’t exactly the answers you want to hear! We’re iterating on the notifications system pretty quickly at the moment, so you could submit any ideas for improvements you might have through our official product feedback form so that our product team can see exactly how you’d like this feature to work!