I'm not a researcher, but I do have some thoughts on this. Some managers assume that if they can't see you, then you aren't working. This is possibly true for some employees, but I believe bad employees aren't only bad if they work from home. They're likely just bad employees all the time and now they can't be monitored. People want to "get back to normal", which could include working from a shared office. However, there can be disagreement on whether what used to be "normal" was really good for everyone. Also, managers need to manage. That is, some people think their job is to make up rules, so if they make up more rules then that gives the appearance that they're really working hard. There are some real benefits to sharing an office. It can make some types of meetings easier to facilitate. It can be easier to get to know your coworkers if you're in the same place.