In addition to that, people are distracted by the virus concerns, and so may be working at lower than 100% capacity regardless if it's from office or home.

The other thing is that people might just treat this period of WFH as a temporary distraction (caused by external forces out of your control), which justifies lower productivity and a bit more goofing around than usual. Kinda like various company internal events, fire drills, or those weird days when things just aren't normal and internet is dead / you have blackouts / office renovation / maintenance that takes a lot of stuff you need for work offline...

It's a different thing when you go into it with the attitude that 1) it is permanent 2) you're expected to be productive as any other full time employee on normal days, onsite or not 3) you'll be fired if you goof off too much.

I require decent soft ear plugs with hunting earmuffs at home because kids and wife.