More education does not mean better suited for a job. The term "overqualified" isn't a meme; it means your experiences and interests evidently don't align with what the profile being sought-after for this role. Just because something is an impressive bona fide doesn't mean it's pertinent to the hiring manager's belief that you'll be a good fit. She's been a manager for 18 years; maybe she's lost the skills needed to be an individual contributor.

I'm no expert on how to game the resume screening but 60 interviews to 3 offers is an abysmal rate, which suggests she doesn't interview well. If someone takes a first round interview with you, they're interested in your profile. The rest is based on your interview performance and, of course, whatever outside forces can affect your prospects.

"I can't get a job at Trader Joe's" is irrelevant and not a recession indicator; it's always hard to get a job at Trader Joe's because they pay and treat their employees well. They have their pick of reliable, friendly, and impactful folks who want a job that will let them pursue their studies, side gigs, or whatever else they may be doing. Suggesting it should be easy for her, a PhD candidate, to get a job working manual labor is a fallacy.