April-May was the time period when prices across industries collapsed. Businesses were anticipating this massive recession and cut back production / dumped goods onto the market in preparation. When the opposite happened, and demand for goods spiked hard, lots of places were caught with their pants down, having already reduced production and laid off workers.

So there's going to be a lot of economic "whiplash" in comparing YoY metrics over the next few months.

You can see the effect here in cars sales:

https://www.goodcarbadcar.net/usa-auto-industry-total-sales-...

Apr 2020 was the lowest sales month by a healthy margin going back to 2005.

Different industries saw this same effect over the April-May period. You can see the looking at the performance of the total US stock market:

https://www.marketwatch.com/investing/fund/vtsmx

March-April prices collapse, and April-May, its on the upswing, by September, there's a total recovery.

https://www.marketwatch.com/investing/fund/vtsmx

Did you do a lot less shopping in May 2020 than normal? Less shoppers risking it at Best Buy might have led to lower prices, but selection bias means a lot of us good citizens who stayed inside didn't see it.

Not really. But then again, we mostly shop for food, which is where I noticed most of the price increases. I would say our grocery bill is now around 30% higher than it was pre-pandemic.