Has the rate of papers uploaded to arXiv changed due to Covid-19?
I think it will be interesting to study this 5 years from now, but right now is way too soon.  At least in math, people don’t post papers at a steady, constant rate.  I personally post around 3 papers per year, and most of those represent work that is at least a year old (often much longer than that) by the time I get around to writing it up.  Given what I’ve got partially written right now, I suspect that I will post about the same number (or even a little more) this year, bit that’s just part of the ebb and flow of research.  What is harder to predict is the effect of all this chaos on the production of new math, which won’t be visible for several years.