In my experience productivity is up and people get their work done. What I do see is a lot of extrovert getting depressed because they no longer have access to the smorgasbord of interactions at the office. Certain managers also seem worried by this move to remote, since it has become harder for them to "play the game" of office politics.

My own opinion is let the people decide what to do. Once a week, everyday, once a month, only when needed... Let people and teams decide.