Playing devil's advocate, if they want people back 3 days, then they have every right to request that. If people are on an office based contract, i'm not sure what the argument Whether it is right/productive is a different question, but they're the ones paying the wages. We were told at our place to be back 3 days in the office, and while people moaned at first (myself included), we did it as we want to keep our jobs! Civil servants threatening to go on strike as they are being told to go back 2 days is a bit cheeky IMO.
At our company, results/productivity actually improved when people worked from home as they were doing longer hours as they were working their commuting time generally. Personally, i think 3 days is a bit much, 2 days would have been my preference.
There will always be people that take the piss though when WFH, those people should be dealt with on an individual basis. I've kinda drifted off on a tangent here!