IIRC, ON has 14 million+ population. 12,000 leaving is a nano figure.
But the point the article makes is a fair one. You can't afford to buy a house in Southern ON anymore. If that's the case, you may as well off to Nova Scotia or PEI, espec as you can work from home in the computer age.
I know several people who left TO to avoid the lockdowns last year. Some went to live with their folks in small town ON. One escort rented a dorm room in Kingston (Queens was closed and doing virtual learning, so I am guessing accommodation was super cheap) and attended York remotely while socializing w her bf in Kingston. (Okay, it IS Kingston. It probably wasn't that much fun). Another escort moved to K-W for much the same reason. Both girls told me that they also spent time in NS and NB during the lockdowns.
Another well known Twitter indy bought a large country property in NB.
So the pandemic probably impacts those figures to some extent.