I can identify with this. I went on early retirement (5 years ahead of time) because I was sick and tired of an open-plan office that kept distracting me constantly. If I had to get something done seriously quickly, like consolidated month reports etc, I had to do it from home. My productivity was at 50% or less at an office because of constant interruptions, or colleagues talking at the desk next to mine.

And of course senior managers would have their own offices, so they could get work done.

The rule should be, if open-plan offices make so much sense for collaboration etc, then everyone gets an open-plan office, including HR and the CEO. They can also go meet in a meeting room for private conversations.

It's easy to make decisions for employees when you don't have to follow those decisions yourself... want employees back at work, yes then make it better for them.