Thanks for asking this, it's super-important to understand it. If they're not infation-adjusted, then there's already been a (very slow) exponential reduction in the cost.

I think they are inflation-adjusted. Here's an inflation-adjusted source that explicitly lets you pick FY2021 dollars as the reference:

https://aerospace.csis.org/data/space-launch-to-low-earth-or...

It puts the Saturn V at $5k USD/kg, the same as this article.

What's interesting is that it shows a general downward trend a little more clearly than this one does, but the Falcon 9 and Falcon Heavy are still very shocking outliers.

It's surprising not to see that anywhere — it's the natural question.

Not at my computer, but this function in mathematica would help:

https://reference.wolfram.com/language/ref/InflationAdjust.h...

They seem to be unadjusted. The source link under the picture links to this dataset:

https://docs.google.com/spreadsheets/u/0/d/1TPewJ64QNVtM5sbR...

There's a column there for inflation-adjusted prices, but not much data in it.

This seems to support it being adjusted not unadjusted. There is no unadjusted column and the Saturn V is listed as 5400 adjusted which lines up with the graph, if it were the unadjusted number it'd be ~7x off.

There is a source link in the article that shows a spreadsheet that claims to be inflation adjusted

Edit looks like it was updated minutes ago

Just updated the figures to be inflation adjusted.