It is true.
If anything, the origins are not entirely clear, as generally tends to be the case with viral memes. But the first two hits that come up from Google have this under their straplines:
'The "Karen" meme is being used to describe women who commit acts in public that are perceived to be racist'.
'In African-American culture, there is a history of calling difficult white women or those who "weaponize" their position by a generic pejorative name. In the antebellum era (1815–1861), "Miss Ann" was used. In the early 1990s, "Becky" was used. As late as 2018, before the use of "Karen" caught on' …
You conclude your post wtih this little belter:
If people ever bothered to look into the actual origins of the term they would see the culture it was developed in and how horrifically racist it was. Maybe they would stop and think about whose words they were using and defending.
You quoted the post of mine to which you replied above. In the second line, I state: I'm one who does object to both the ageism and sexism embedded within that term. I do not use such terms. Far from defending them, I've taken issue many times with those who do. I'd challenge you to find a single post of mine in which sexist pejoratives like 'Karen', 'bitch' or 'cunt' are ever used. I'll wait. I suspect I'll be waiting for a long time.
The disingenuousness and 'spreading of misinformation', it appears, is all yours.
It's reappropriation of every issue highlighted by black people to describe their experiences, and the cavalier dismissal by some people of the experiences of others who don't look like them. No wonder books are being written with titles like 'Why I'm no longer speaking to white people about race'.