Karen's are not in my experience being denigrated for "having an opinion". They are rightly denigrated for raging at store workers, calling the police on black people for gathering at a public park, or gardening on their own property, attempting to enter their own apartment buildings, using their own apartment complex swimming pool, working at their own job site and being accused of "not looking like they belong there", and on and on it goes. Abuse by white women who think they have the right and possibly the duty to question any black person for doing anything they deem "suspicious". Who think police have no right to pull them over for traffic infractions because they are an elected official or a public figure..seen a few of those.
Do try to watch Karen compilations on you tube and you will see what I'm talking about. A lot of the Karen's recently have been anti-maskers taking their rage out on store employees and end up being arrested, my opinion is that this is their intention, as many are photographing themselves.This is not "white women having an opinion". This is people purposefully thinking their own opinion trumps (ha ha) everyone else's and everyone else's rights, and that they have a right to create scenes and force police to be deployed to remove their uncooperative unruly selves from private property.
Not all Karens are white women.
But entitled white women are the stereotypical Karen, at least here in the US.
As for Shaniqua, not sure when it started, but it could have been the movie Crash. When a black woman responsible for helping a white racist man get help for his father who was deteriorating medically, told him her name was Shaniqua, he responded "Of course it is."
Crash is a movie that explores everybody's racism and how all of it interplays with events.
Shaniqua does end up helping the racist white guy when they both were able to see themselves as fellow humans.
I don't see the use of Karen as being misogynistic. I see it as a shorthand for "entitled usually white woman doing something abusive". It's certainly less awful and definitely more descriptive than being called a b#tch or worse, isn't it?
Sorry to all the actual women named Karen out there. Lots of perfectly good names have gotten a bad reputation.