I am curious how you measured your productivity. I do think that a weakness in the published data is that methodologically it's tough to measure productivity if work isn't done in clear, countable units, so only some kinds of work gets studied. And clearly teams struggle with picking the right metrics for themselves, carving tasks into the right sizes, etc.
Just Jira burndowns. We tracked ALL our work as tickets. Obviously story points aren't rock solid indicators, but we were basing it off a couple of years of data. For months before the pandemic there was a pretty solid line, then after months of working from home that line visibly raised. The org, who didn't look at our Jira data, also commented that stuff was coming out quicker. Of course there could have been other factors too, but that's what we saw.
