Age demographic

This is something that greatly affects a country and isn’t accounted for. For example, in my own country we are seeing “the baby boomers” all retiring. The effects this is creating are

A significant drop in income tax revenue, especially since a lot of these people were middle or high earners
A skills shortage, as a whole lot of the most experienced workers are leaving all at once
An increase in state pension costs
An increase in state health service costs that is just starting now, but will get really bad in about ten years.
An increase in the percentage of retired voters

There’s probably more, but those are a few I could think of in 5 minutes.

Birth rate bubble.

Strict Abortion laws, benefits for having children, marriage tax incentive should increase it. An increasing birth rate should increase costs of government spending on education but increase long term economic growth. Maybe even a baby boom green bubble and baby bust red bubble.