Proposed solution: Adding an option (that per default, it should be disabled) at Special:Preferences#mw-prefsection-echo. If you choose to activate that feature: if a CSD tag is added/removed in/from a page, you will receive an alert about that. In order to work, all CSD tags should contain "<includeonly>__ECHOCSD__</includeonly>" (the adding/removal of this magic world should trigger the alert). If there are added more than one CSD tags in page, you should receive only one alert, to prevent spamming. Also if there are added further additional CSD tags or if there are removed some CSD tags, but not the last (you should be announced only if the last CSD tag is removed from a page). To prevent the adding of __ECHOCSD__ magic word without a CSD tag, it should be created an abuse filter which stop other users to add this magic word in a page, but allows them to place it if they place a CSD tag.
More comments: Something similar it could be created for unblock requests.
Why a notification? Is the intent so that you can go in restore the speedy deletion template? Why not use AbuseFilter to prevent this from happening in the first place? Another option is to tag edits that remove speedy deletion templates for later review. MusikAnimal (WMF) (talk) 17:01, 18 November 2020 (UTC)Reply[reply]
Additional, you could receive an alert if a page created by you was deleted, it was marked with a CSD tag or the CSD tag(s) from a page created by you has/have been removed. --NGC 54 (talk / contribs) 17:47, 18 November 2020 (UTC)Reply[reply]