I wonder if maybe someone had that domain and then deleted it. Dynadot(and probably others) for example lets you delete domains for a partial refund within a certain limited amount of time - which I think is a neat feature.
I know there are historical whois sites, but as far as I know unless someone in the past checked for the domain with their service, they'd have no record of it otherwise. So maybe that would explain how it has a cert for a domain that currently does not exist and appears to never been registered.
That might be possible. A lot of these "domain info" sites receive a daily feed from the registries (i.e. Verisign) that include all domain registrations, renewals, etc., so I would think they'd have it in their database even if that happened.
What is unusual is that if someone had it and then deleted it, it doesn't still show up in the whois records in a 30, 60 or 90 day redemption period. From dealing with a few .net domains that recently expired and went into redemption, it takes a long time for a defunct domain to actually disappear and become re-registerable again by another totally different purchaser.
Redemption period I know of for when domains expire. But if you do the grace deletion it's pretty much instantly. I was debating on a domain once with myself, deleted it and then a day or so later registered it again. Usually you can delete within the first 118 hours on certain tlds.
https://www.dynadot.com/domain/grace_deletion.html has some info about it. I'm only familiar with Dynadot because I use them, but other providers that offer this should have similar information and times.
I know there are historical whois sites, but as far as I know unless someone in the past checked for the domain with their service, they'd have no record of it otherwise. So maybe that would explain how it has a cert for a domain that currently does not exist and appears to never been registered.