The story
From the use of Karen, beginning in the late 2010s, as a pejorative for an entitled middle-aged white woman. The association of a specific hairstyle with this type of woman began with a meme in 2014 pairing a photo of a white woman with an asymmetrical blond bob with the text "The 'Can I Speak To A Manager' Haircut".
Etymology from Wiktionary, CC BY-SA 4.0.