I do think many of the WFH productivity gains seen can probably be attributed to 2 things:

1) Many workers (but certainly not ALL workers) had a much more quiet and focused work environment at home, compared to their buzzing open-plan desk in the office, making them more productive.

2) COVID severely limited socializing, so some people poured that time into work out of boredom.

#1 is constant, and might get better for some when schools and daycares fully reopen.

#2 is starting to go away and will be gone by next year.