Anecdotal: I run almost every day. Don't get excited, only 2 to 4 miles :) Early in the pandemic I saw plenty of new faces - often couples - out exercising. Some running, mostly walking. I don't see many of those faces any more.
Neither do open gyms. :)
Though post-holiday covid peaks may have slightly altered the long-running wry observations about January in the gym.
But there were some very cautious times during lockdown. Events like Parkrun were cancelled for months on end. Loads of races were cancelled. Gyms were closed. Indoor fitness activities like dance, yoga, pilates, and aerobics were cancelled (and their online alternatives much more sparsely attended). If the place you were doing swimming/squash/tennis/golf is closed, you're out of luck. Football, hockey and basketball aren't compatible with social distancing. Neither is boxing, judo or MMA. People who commuted by foot or bike started working from home.
Running and cycling were certainly winners, but I'm certain there were a lot of losers as well.
* increased personal time for workouts for anyone working remotely (or forgoing employment entirely)
* dramatically increased demand & prices for home exercise equipment
* shifts to cooking at home
March / April 2020 seemed to be marked by a lot of people going outside and running. Personally, I shed over 35 lbs of bodyfat in 2020 and have had few comparable periods where I hiked as often or ate as cleanly, and I'm far from alone in my circle of acquaintances.