One important thing to remember here is that it is easy to read our own beliefs and preferences into things like this. The truth is, I don't know why people are moving. I do know many people that left cities due to crime, expense, and response to Covid. But for each person it is likely going to be different.
The fact does remain that regardless of the why, most of the core reasons are being influenced by city government policies even if those moving aren't consciously thinking of those root causes. Higher expense is mostly due to city polices. Crime is mostly the city gov fault. The city policies and lack of space are also due to gov polices.
So in the end, the city is ruled by the government of the city. They are failing to keep many happy enough to stay. The Internet in rural US is getting better and this is opening a door for many to opt out of living in the city, or at least large cities.