Isn't there a 12-14 day lag from infection to death in average cases? Could the Sunday dip be some kind of harmonic?
Daily percentage of new Corona virus deaths to previous day's total by country. 25% = total deaths double every 3 days, 20% = every 4 days, 15% = every 5 days, 10% = about 1 week, 5% = about 2 weeks.
“What’s up with Sundays? Any ideas? “
My first suspicion is that not all counties or locales in each state report on the weekend, or at least not on Sunday. Union rules or something.
I’d look for the states that have Sunday dips. My WAG is southern states like LA or GA with hotspots.