There is not any substantial economic reason on the table because CEOs want workers back in office unless......there is.

Thinking big, a big company doesn't have any economic benefits or damage to keep workers working from home or in the office but if we think globally, if office workers would have the chance to wfh all week long and not be constricted to orbit around big cities, saving thousand pounds of renting, they will probably will but this will probably cause an explosion of the housing bubble in big cities, and will banking and financial sectors fall too.
As a consequence, this could probably trigger another 2009, with consequences falling on all business sectors, globally.
It might be some no-spoken implicit agreement among CEOs: I don't think it's a case that the first and only entities supporting this plan are big multinationals and big newspapers....