Mike Moffatt, It’s mostly young families, not retirees, leaving Toronto, February 2021.
The Toronto figures are particularly eye-popping, with large losses of young children and people in their 30s, with a small net-inflow of college-aged Ontarians. The most common age to leave Toronto is 0 (that is, children under the age of 1), the ten most common are between 0–4 and 31–35.
A related CBC story this week (about younger people leaving the province entirely): Ontario's young adults are leaving the province in droves. The soaring cost of living is to blame. It was posted to r/ontario and got a lot of attention.