My 6-year-old brain thought that it was like a tumor or something
In fact, the script specified that it be pronounced “KAY-nar”: https://www.st-minutiae.com/resources/scripts/186.txt So that must have been forgotten/changed at some point, or maybe it is the auditory equivalent of “whisky” vs. “whiskey”.
Very interesting! I had been planning to look up the episode to see for sure, but I forgot to do it.
The pronunciation they ended up going with rolls off the tongue a little easier for me, so maybe that was the reason. I don’t remember the first DS9 episode to mention it, but I remembered it being in 2x21 The Wire, so I looked that up. https://www.st-minutiae.com/resources/scripts/441.txt By this point it had been changed to the more common version.