User disappeared after power failure?!

Hello guys,
Board is RBD52G-5HacD2HnD, fw ver. 6.44.3, WinBox ver. 3.18.

After a couple of blackouts, everything seemed to work normally, but today when I tried to log in with my username, it gave me “wrong username and password”. Also tried ssh and web admin, but the same error appeared.

Finally, I tried logging in with the default admin user which succeeded and found out that the admin user I normally use is gone.

Is it possible this could happen because of a power outage? Everything else seems to work normally, I don’t see any indication or got any alerts that anyone has logged in and done something. I also browsed through similar topics and it seems some older versions of WinBox have an exploit related, but mine is the latest, so shouldn’t be the case.