Its getting ridiculous then... Cant see a good excuse for that to happen except... somekind of mumbo jumbo called timewarped distortion or some shit like that... :crazy:
Here's a few ways I could see it happening, and keeping fairly true to what came before:
1) Changes to the timeline due to outside factors. More of a cop-out than anything else though. Way too clichéd and over-used.
2) Multiple sub-species of Klingons. Hard to reconcile why they would not have been revealed before though. Would help to explain the different ships as each group has its own dominant designs.
3) The Disco Klingons were an experiment in trying to overcome the side effects of the cure to the augment virus from Enterprise. Their failure in the war (or just how they ended up fracturing the Empire) led to discontinuing of their lines, restoring the Klingons to both the standard original movie/TNG/DS9/Voy era Klingons, and those affected by the cure to the augment virus. The latter come to dominate the Empire for the next decade or two as it focuses on the Federation, explaining why they are the only ones seen in TOS. This doesn't explain the vastly different ship styles between Disco and what came before.
4) Disco actually is actually an alternate universe from both the Prime and Kelvin universes. This could actually go with any of the above as well.
5) Something else entirely, and distinct from the above.
Ruger