Wait - If I throw a bowling ball really fast in a vacuum, does its temperature increase?

That's what I'm suggesting - the catastrophe proceeded to the point that all members of the cluster were either ejected (far away enough to be indiscernable relative to the quasar) or absorbed by the quasar core.

Thinking some more about it, there are probably some ways to constrain the amount of time it takes for a past runaway to have occurred that rules this explanation out.

It probably got kicked out of it's host galaxy during a merger.

I was just watching this: https://www.youtube.com/watch?v=c1sZpSoMq5g

And, apparently, poor lonely black holes can evaporate over time?

Is that necessarily true in the earliest moments of the universe? Probably there are good reasons for it to be so that I don't understand, but then most of what cosmologists understand about the period that JWST looks back to is from extrapolating backwards, and it seems like the new observations it has enabled keep disagreeing with previous assumptions. Anyway, I really look forward to finding out what improvements to theory can be made to better explain anomalies like these lonely quasars or the apparently overdeveloped young galaxies.

If they did they’d be invisible, which is why isolated primordial black holes with a variety of masses are a dark matter candidate. A quasar would be one with a giant accretion disk right?

Maybe a theory of hard-to-observe Dark Suction will come to the rescue

Well, the accretion disk surely runs out at some point, and just before that point, shouldn't it look like a quasar in surprisingly empty space?