"a normal effect of recessions is for productivity to increase; businesses lay off workers and then try to figure out how to run their operation more efficiently with less workers, that happens in every recession"

This is not true. In fact, the normal effect is the opposite- a productivity decrease. See the data for the US after 1948 here.

If you are looking for a story as to why, in some business cycle theories (such as Real Business Cycle Theory) the recession is caused by a negative shock to productivity.