Again, language change happening under our noses. Around 1950, most people would have said that the past tense of dive is dived. Now dove is more common. This is perhaps under the influence of so much time in autos and drive/drove, ride/rode. Language change often moves in the direction of assembling similar-sounding words under similar rules.* We used to prefer to use sneaked at the past tense of sneak, but now mostly use snuck. Even more recently, the use of sank for the past tense of sink is giving way to sunk, even from official news sources supposedly relying on one or other of the manuals of style.
There are regional variations in how quickly these are happening, but they seem to be happening throughout America. I don't know about Canada and Australia. Also, these forms existed before 1950, but were not dominant.
I think of dived as something old-fashioned and believe I have always preferred dove. But snuck sounds slangy to me and I would still use the other form. I use sunk only with the "helper" verbs of "was sunk," "had sunk," etc - that is, as a past participle. At least, I think that's what I do. Sometimes when things are undergoing change we find that we have begun intermittently switched over without noticing. I sink, I sank, I have sunk is what I believe I invariably say.
Once a form is accepted as preferred, it is long before it is called incorrect. It will be marked archaic instead. The forms that get called incorrect are the rural, the provincial or regional, and the new. Old forms just slowly slip away without our fully noticing, like a celebrity who dies at 96 and we say "Oh, I thought he had died years ago."
*Could got an l in its spelling for no reason except that it looks and sounds like should and would. No older form or root for it had the l.