No that is actually somewhat the explanation why they look more human. It is explained in Enterprise, the Klingons try to create some super soldier serum, but that kills them. Phlox helps them create a cure, but that makes them look more humanoid. I think at the end of the episode they say that it might take centuries to revert this effect
Enterprise established it as a result of Klingons experimenting with human augment DNA and it getting out of hand. It probably didn’t need to be addressed in universe, but I thought it was a fun retcon.
Klingons look very different through the various shows. And more than just costuming progress of the time.
TOS:
TNG-era, the one I think most people would think of:
Discovery:
And the latest show, Academy, reverts back to TNG-era style Klingons.
Is the cannon explanation for tos to tng change being a skin disease or something that has infected the whole population?
No that is actually somewhat the explanation why they look more human. It is explained in Enterprise, the Klingons try to create some super soldier serum, but that kills them. Phlox helps them create a cure, but that makes them look more humanoid. I think at the end of the episode they say that it might take centuries to revert this effect
Enterprise established it as a result of Klingons experimenting with human augment DNA and it getting out of hand. It probably didn’t need to be addressed in universe, but I thought it was a fun retcon.