I tried to classify systemic shifts that lead to changes in the way people or businesses live, and consequently give rise to new problems that can become the basis for startups. For example, a law requiring electronic receipts immediately gave a push to new businesses.
The classification yielded as many as 9 areas - consider their description as an invitation to discuss in the comments)

Media-Psychological
New mass fears, emotions, news hooks. Humanity saw a new TikTok where it says that the mark on the pasta should be green, and everyone ran to look for such pasta.

Political-Legal
Changes in laws, regulations, government procurement, taxes, subsidies.

Scientific-Technological
Discoveries, emergence of new materials, algorithms. Most often affects the cost reduction of some production.

Economic
Inflation, rates, rising cost of capital, shortages - changes consumption. Food discounters where everything is in boxes and products are only extra economy are a direct consequence of the impoverishment of a large mass of the population. It also works in reverse.

Social-Demographic
Aging, migration, changes in employment structure. For example, many startups targeting the elderly are emerging now, especially in China, where there are already hundreds of millions of elderly people. Another example is the robotization of China, a direct consequence of massive population aging with a huge demographic gap.

Cultural
Changes in values, attitudes towards the world, work, prestige, ecology. All environmental startups were born precisely from a change in culture and the emergence of a demand in society; of course, one can argue here, as this is also a media direction.

Infrastructure-Logistics
Emergence of new logistics chains or destruction of old ones, new development platforms, etc. I would cautiously include ChatGPT and vibe coding in general as such infrastructure, which in 2-3 years will give thousands of new micro IT service startups. Well, logistics - the closure of direct supplies to Russia simply gave birth to a bunch of startups for delivery and payment of goods from abroad.