So, I was interested in this statement, and looked into it barely, and on one side, its conclusions were replicated in a number of other papers[1] (despite the headlines, three years after its publication, of a simple calculation error)[2]. I'll state that neither of these points are a slam-dunk if you're a member of one political side or another. If you're a believer in austerity, you'll look at the corroborating studies; if you think that was a bad policy choice, you can argue that they're all junk science, pushed out by supporters of the status quo.

I suspect what it narrowly shows though is that this isn't the same category of error as what's being discussed here.

[1] https://www.mercatus.org/research/policy-briefs/debt-and-gro...

[2] https://www.bbc.co.uk/news/magazine-22223190