This might be the nr 1 reason.

The hidden layoff round is also high on that list if you ask me. They call everyone back to the office, the people that dont want/cant will not adhere, and thus be fired without the companies having to pay severance.

not really. there used to be a system where the SF government of course provided tax benefits for Twitter (now X) and Square (now Block) to open offices to enliven Market Street. Jack Dorsey fell into this trap and actually did establish his office there, until the SF government decided to cash their Golden goose and take these tax breaks away.

and so right after, Square has gone fully remote as well as X has mostly left the Bay area

"RTO is definitely the play: the CEO says all his friends are doing it; activist-investors want RTO for their own porfolios, PR says breaking the lease on our newish HQ is embarrassing while Legal says it makes more work for them; Accounting says we'll pay more in tax unless we can prove X jobs created locally; our middle-managers need it in order to tell if work is happening, and HR notes that we can slim our workforce by prompting a lot of 'voluntary' departures! Seven key stakeholder groups."

"But will the employees be happy, and will good ones stay?"

"Seven to one, my friend. They're just grumbling like always."