You can't measure productivity during the pandemic and assume it speaks for work from home in general. There were a lot of things about the pandemic that caused a reduction in productivity that had nothing to do with whether or not workers were in an office.

Also consider that productivity might be best with employees choosing their office schedule. Some might be more productive in the office five days a week, others zero... and the majority will probably be somewhere in between, spending some days at home and some days in the office.

Bottom line, though: the pandemic is not a good time to measure productivity for any reason, and consider it representative of the norm.