TL:DR, I'm not a big advocate of WFH, but it's a biased opinion.
The bottom line: Perception is reality.
One thing I notice is there is usually a pre-WFH and post-WFH perception.
Firstly, there are two broad categories: employees who have an office, and those who don't.
Things are different when the job never had an office visit, and the gig was always 100% remote, but let's save this situation for last.
For the scenario where people are normally working at the office, when somebody first gets WFH they seem to have a bump in productivity, and I call that phenomena the "novelty phase". We can guess all the reasons, some of the easy things are:
* not having to commute, reclaiming commute time as productive work time.
* fewer distractions from [insert list of distractions at the office], increased focus due to isolation.
* wanting to appear more productive, as to not potentially lose the so-called "privilege".
* better amenities. In essence your home office is potentially way nicer than your employer's workspace. You might have a loud clicky mechanical keyboard nobody is going to complain about, or gigantic gaming monitor, or multiple monitors, better outside view from a window, or even having a window, or great tea/coffee, etc..
* working hours flexibility; you start or stop working according to your combined work & life schedule situation.
* pretty much anything you can compare with working at the office, you can rationalize ways things are better, you're in "rationalization & denial"... well save the denial part for later.
People are more productive during the honeymoon phase, but slowly over time this "productivity bump" diminishes.
* you lay on the sofa, watch TV, or read a book... time gets away from. You potentially start missing meetings.
* other people in the office are having impromptu face-2-face meetings, your sometimes not invited or ever aware... the shift to irrelevance creeps in slowly.
* due to a perceived lack of accountability, some people get lazy, become less productive, and worse... indifferent. They have no stake in the game, or personal connection to co-workers.
* become over worked, actually working more hours of the day, and become legitimately burnt-out.
* sicks days become work days, and vacation hours accumulate to the point people take PTO just to burn hours.
But things are different for people who never worked at an office, because there is no basis for comparison, so all of the above issues are more or less nuanced, or not as relevant.
* when was the last time you were jetted out to a face to face meeting, if ever?
* got coworkers on the other side of the planet? How do those 6am meetings feel, or 9pm meetings? How does it feel not having set hours?
* got your office pimped out? Nice, and who paid for all that, you or your employer? Is that room your work in, was that your personal sanctuary before, but now become a place you go for work? And, as such have you worked on any of the personal activities or hobbies that used to happen in that room? Does going into that room now cause anxiety? A bunch of people choose to work in their so-called "home office" but before that used to be where they played online games, or maybe did hobbies or crafts... everyone's different, but the one thing is the same. Doing work in that personal space ruins that personal space from a mental perspective, and it's insidious because most folks don't realize this until it's onset.