They took data from existing mortgage costs. They did not base the affordability on what it would cost to buy a home currently. Utah has always had very high rates of home ownership and low out migration. Much of the recent in migration has been cash buyers so they don't factor into this study.

They put the median mortgage cost in Utah at $21000. It would take close to double that to buy the median priced home in Utah right now even with a sizeable down payment.

Tldr: an intern seeking a bachelor of arts degree did this analysis