A decent point, but each of those ships were from realities where the Cerritos is that class. Just as there are Klingons who never left Quo’nos or never evolved past proto-Klingons and those crews and ships were affected by the reality waves to reveal them.

I think there is a reality within which the Klingons evolved slightly differently and developed a slightly different culture, but remain close enough that we don’t see major changes to the events of the Prime timeline.

Is it fair to assume that, by showing the Klingon turning Disco, that the implication is that Discovery exists in a reality almost identical to the Prime Timeline, but with differently evolved Klingons?

If so, it begs a question. Is there a Mirror Universe for every reality? Or do they all share one?

The best agent Bajoran TSA ever had.