I love (read: hate) the concept that people are inherently busier in an office. When I was full-time in office, lots of people spent a good portion of their day wandering about, having convos (one thing that I do miss), browsing snacks, playing ping-pong, browsing snacks again, going out to long lunches, etc. I 100% spend more time in front of a screen when wfh, and when I do step away it's to get other "life" things done instead of killing time in-office until the clock hits 5PM. I am also far more likely to work early or late, as I no longer feel that I have to clearly delineate my time between work and home.

This is definitely an issue with lots of subjective and anecdotal evidence on all sides, but I know for a fact that a lot of my coworkers were killing 3-4h/day in the office just doing...whatever.