Just as a counterpoint of anecdata, I saw more or less the opposite behaviour when I was at Dropbox during the pandemic -- I heard from my coworkers more than I ever did working in-office, and was better-connected to the work they were doing. I personally felt more productive, and most of my team seemed pretty productive.

The downside is that a junior teammate was probably less effective than they could have been because of a lack of in-person mentoring -- their learning was slower than I would have expected in-office, but, then, that could be this particular person rather than remote work.

I don't doubt your experience, to be clear -- I just mean to say that I think the situation is more complex than "people are less productive" or "people are more productive."

Seems like that's a failure to set and enforce expectations.