I think whats happening is that non-technical leaders can't assess why projects aren't being delivered. No engineer is going to say "sorry I wasn't really working that hard, thats why we missed". Instead there will be some rationale as to why the project couldn't ship on time - not enough resources, incomplete spec, tech debt, whatever. Non-technical leaders want to be able to remove one variable from the equation - the cause being the team didn't put in the effort. With return to office, they can see with their own eyes if people are putting in the "time".
Which says a lot about the leadership. :-)
So there might be a long term benefit to the team, even if individual productivity of high performers goes down slightly.
Holding someone "accountable" means firing them very quickly for a drop in performance. This is hard in large companies for many reasons.
The only way I've found of doing this accurately is to reassign a task, IE if something is taking dev1 what you perceive as too long, assign it to less experienced dev2 and see if they can complete it from scratch in less time. If so, you know dev1 is subpar or slacking and should be RIF'd.