It's become pretty commonplace in office environments in the last few years. My company did it, and we develop medical communications literature. They just decided that, as more people were working remotely after the pandemic, it was just more efficient not to renew the lease on most of the office space, and not to bother having assigned desks if people were coming in just a few days a week at most.

Of course, my company never made it mandatory to come into the office (esp. because most people worked all over the country, nowhere near an office); I don't know Meta's situation, if they forced people to come into the office but didn't provide a permanent workspace--which is entirely what I'd expect from them--then they deserve to lose all their employees.