Based on the source, it uses the same exact data as the NYT one, though with more of the questions from that original Harvard Dialect Survey. I imagine the NYT one just narrowed down to the questions which would have the strongest correlation for the final results, and based on the maps I see...

2002-2003: Bert Vaux and Scott Golder run the Harvard Dialect Survey 2013: Josh Katz does a new survey using questions based on that one and uses that data for the NYTimes quiz 2026: Tim Stumbaugh and Jenil Kansara use an AI agent to create mydialect.us using the 2003 data at dialect.redlog.net

Anyway, a project I've been on and off typing up over the past couple months is a big list of all the basic web design elements that in my opinion give away a website as having not been designed by a human. I've enumerated these as "The 5 Tells of Vibe Design":

note in this that I quoted I said it was the same exact data, but later down in the thread I find that it's per state, the raw data must have been used by the NYT version but it's not easy to find online, so presumably whatever AI agent they used decided it wasn't worth it