Optometrists blame increased screen time.
My top suspects would be wearing full distance vision corrections in front of the screen and spending too little time outdoors.
I’d also add smaller and/or cheaper screens (or just using laptop screen), decreased distance from screen (smaller desk, or just working from the dining table, or laptop & sofa…), worse lights around the working area (home feeling instead of the offices’ and schools’ lovely white lights). And maybe more heating resulting in drier air, too.
I think the initial enthusiasm about going for a walk every day has mostly passed by now.
The good news is that it is never too late to correct habits