I've seen this attribution of RTO to "managers" before but it doesn't ring true in my experience. Managers is too broad of a group of people. Every manager I've had since the beginning of the pandemic has loved working from home and said they don't want to go back.
If this [1] story from a few weeks ago is to be believed these directives are coming from the people at the top: executives, high level management, and investors. That story is about Microsoft specifically, but I don't see anything in there that would indicate the same couldn't have happened at other tech companies.