Through yet another delightful glitch from the game's interlocking systems, this explorer somehow managed to register The Key, the prime stronghold of space pirates the Crimson Fleet, as a ship in their collection. Which is concerning, seeing as it's a space station. You know, those big megastructures that are built to live in space? It's not exactly made for dogfighting.
When asked how in the Great Serpent's name they did this, VeganSatan666420 replied "Still not really sure. I sold a stolen ship to the pirates, then went to change my home ship and it let me register The Key."
It remains a mystery—selling a ship in Starfield is a touch convoluted. You need to register ships before pawning them, even when fencing to pirates like the Crimson Fleet, who have a surprising respect for bureaucracy. I can only assume some flag in the game code jumped from the plundered vessel to The Key itself.
Another player by the name of kingarchee reported a similar issue, though for them it made for more of a hindrance. "I had this issue during Red Fleet's quest when instead of your ship you fly the prison barge. I finished the quest, saved while still on the Key and went to sleep [in real life], next day I can't travel anywhere because The Key is my home ship and the option to change it is gone."
The Key is basically useless as far as ships go. It has a baffling cargo capacity of zero, no shields, and is apparently worth nothing—obviously this was never supposed to happen, so Bethesda didn't give it a sale value, but the idea that the rugged jewel of the Crimson Fleet is unsellable is very funny: 'You stole what? No I'm not buying it, I don't want anything to do with this.' While VeganSatan666420 describes it as "not really flyable", something which I feel must surely be an understatement.
I'm noticing a pattern here of staryards and space stations producing wild outcomes, like the Deimos Staryard occasionally becoming the system's punching bag. Maybe they're like cryptids, and we'll see an SCP-style wiki gathering all their strange behaviour—or maybe it's just a small example of the charming weirdness I enjoy in Bethesda's messy, sprawling games.