It's difficult to be productive when you're waiting on a shipment of parts, for one thing. We've been working for decades to make industries work with more advanced logistics and less stock on hand. Now there are supply chain issues, and you can't assemble and sell something if you don't have the parts whether it's a car, a computer, or a rose hip half skim gigante honey latte.
Real wages are up a bit, but revenues are way up despite the supply chain issues. People are being forced back into offices who don't need to be there. Maybe morale is low. I know of concrete instances of low morale, and I'm sure there are others.
People's life changing because of RTO requires attention.
People are often looking to move or to change jobs recently, which requires attention.
Millions of people have been ill with a respiratory/vascular virus which sometimes causes long term damage. More than a million in the US have died from it. Survivors often have pulmonary issues and long-term mental fog which may be permanent or take years to recover. They have less energy and stamina. It's harder for many of them to concentrate. Some of those who died were in the workforce, and whatever knowledge they had about their job died with them. Other deaths were people's family and friends. Funerals, cleaning out houses, donating their belongings, and the grief itself aren't exactly good for worker productivity but they are things humans need to do.
Lots of micromanagers exist. For people who haven't returned to office with no open floor plan to walk around, many of them use a messaging app like Slack to micromanage. Water cooler conversation is in Slack channels. Meetings are in Slack, Teams, or Zoom or something else, and everyone's supposed to be engaged rather than working on their laptop until it's their turn to speak. There are often more officially designated meetings because people can't drop by one another's offices. Lots of work is concentration-based work, or "flow" work. Constant interruptions are bad for anyway, but when it takes 20 or 30 minutes to get all the context in your head to solve a problem and a three-minute interruption to lose all of that, more interruptions can be catastrophic for productivity.
Some types of business have minimum staffing requirements. You can cut staff and try to "right size", but you need enough staff to keep the place open if that's your goal. If orders are down enough, your staff will sometimes have less to do. If because of the shortages mentioned before your ability to fill orders is down, the same thing applies. You have a choice of eating some less profitable quarters until the supply chain levels out or just closing shop. You can't lay off 100% of your trained staff and count on rehiring them later.