The impact of the pandemic on the underground economy

Dan Murphy emails me:

I’m wondering if the pandemic is having an outsized effect on the underground economy relative to the economy as a whole.  For instance, many of the small businesses that are shuttered or scaled down would be more likely to engage in unreported cash transactions than the online retailers who have thrived.  One further, consumers purchasing from small business are less likely to use cash as payment for sanitary reasons or because their payments are processed through Seamless or Uber Eats.  With estimates of the size of the underground economy between 11 and 23%, could a 10-50% reduction in these transactions mean we are significantly underestimating the size of the slowdown?

Any thoughts?  Any pointers on further discussion?

Do any of you know of good treatments of this?