From the article
Bolhuis et al. then went on to see if they could recalculate the official CPI numbers using a pre-1983-like formula that incorporated the cost of mortgage interest, auto loan interest, and credit card interest on the cost of living. They found three things: first, that the pre-1983-like formula led to a dramatically different estimate of inflation in 2022 and 2023, peaking at 18 percent in November 2022