Legacy API password user

I’m doing a long overdue hardening of my HA security, e.g. enabling mutlifactor authentication, etc. Long ago, I had used the API password in configuration.yaml, but vaguely recall removing that when it was deprecated, and stopped using it.

Well now I look in the UI at Settings → People → Users, and there is an active user “Legacy API password user”. It’s in the Administrators group but has no Username nor can I change the password (“No Home Assistant credentials found” when I click Change Password). I don’t think I use it but I have no recollection of where this came from.

I’m hoping someone might have some pointers, like it was created automatically if you ever had it in the yaml, or somewhere to check a last used date, or something. I.e. is there any way to vette this other than turn it off and see what breaks? I tried searching but everything I found is ~5 years old about the yaml option.