The article quotes that 28% as being the amount of inflation "from 2010 until the middle of 2021". I haven't checked the figures, but that seems believable for a decade's worth of inflation.
Re:A note for LWN subscribers
by bryanlarsen on Thursday January 20, 2022 @10:07AM
(#30009778)
7% is from 2020 to 2021. 28% is from 2010 to 2021.
https://www.usinflationcalculator.com/
Try typing in "2010" and hitting calculate.
> will increase to $9/month, which is almost exactly in line with that mid-2021 inflation rate
I don't believe that the mid-2021 inflation rate was 28%. Sources† say it was actually around 7% (which is, admittedly, bloody insane).
† A DDG search and looking at the top 5-6 articles