People start dying off, and all of a sudden housing prices go down. There's more parks open. The air feels fresher gradually. It's a gradual decline as human influence tapers off near the end. I think it will be more "The Last of Us" than "Mad Max"
Humans living through an event where many people are dying will not be calm and happy, they will panic. There will be factions of people trying to survive and hold society together no matter the cost, others who don't believe or agree with these methods and actively resist, as well as those who seek to exploit the chaos.
COVID was a relatively minor example of this, not even close to an extinction event - how pleasant was existence during that time?
If not for modern comms, I am convinced that even in a cold war USA vs USSR style aniliation event, there would still be a handful of people on the far corners of the earth who would otherwise take weeks or months to learn anything happened.
To use your COVID example, most of us living well outside the cities and suburbia were very little affected by it. The biggest inconvenience I remember was having to go to Walmart at 6:00 when it opened to get a chance at buying toilet paperl
For me it was mostly terrific. We had increased streams of revenue and were food secure for the first time in a decade. Meetings I dreaded due to crowds were streamed online.
And the roads were blessedly, amazingly, wonderfully travelable.
The housing crisis in 2021 was another matter entirely. Our long term rental was sold and what few listings there were got 400 hundred applications - every day.
2020 was excellent for us. 2021 was a slow moving, panic-strewn nightmare.
I will assume this is true and plug it into our falling birthrates.
People will flock to cities that still have services. Then the cities will have the same population density as before.
Ted Kaczynski had a point...