Are changes to the user status stored somewhere? I've made a pretty serious error of judgement creating a view for a client that shows users created before a date AND still active. The error was adding a date filter.

This was meant to be used at the end of each month, and it was, with an email of users sent to the client. Now, after many users have been blocked, they're showing back on the view I created.

With quarterly billing, this is an issue as new users get counted fine, but any old users who have been blocked since don't show. A year from now, this period could actually show zero users.

The accounts were blocked using the editable_fields module.
Core doesn't store revisions/changes for the User entity type (the functionality simply isn't available out of the box).

So unless you have something like the User Revision module installed, or some custom functionality storing that data, you're unfortunately out of luck.

If you take regular backups, you might be able to fudge something together using those, but it would be a very manual process.