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?
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.