Deactivated users are sometimes not being deactivated

This is still happening sporadically. For example, this user was initially “deactivated” on August 23, but I just noticed now that they were still active and actually deactivated them.

How can a user be deactivated twice (without a reactivation in between)?

I have a daily task that runs a query to check for this situation. It returned nothing yesterday and this one user today, so what seems to be happening is that the user was correctly deactivated on Aug 23, but it somehow got activated yesterday (without it being logged anywhere).

Is it possible to activate a user (via API or UI) and not leave a trace? I’m assuming this could only happen by modifying the database directly, which I’m certain I didn’t do (I’m the only admin).