The problem is manifold in its aspects which means there isn't such a clear cause-effect link.
1. countries really don't like being dependent on other countries for feeding their population - the current Russian invasion in Ukraine and the issues surrounding their grain exports have shown how bad such dependencies can get in the worst case.
2. basic agricultural staples - potatoes, grain, rice, but also eggs and milk in powder form - are a global market these days, which means there's a ruthless competition in place, made worse by at least the US and EU doling out insane amounts of subsidies for their farmers.
3. in some markets like China, scandals around food are the norm, which in the case of milk powder led to second order effects like Chinese tourists and expats in Western countries buying up milk powder at scale and shipping it back to their relatives in China - which led to a massive increase in price in affected Western markets, and to the political question if governments are effectively subsidizing China's issues at the cost of citizens.
4. Western masses are getting ever more poor which puts an insane amount of political relevancy to the price of food (see e.g. the current egg issues in the US). At the same time, both distribution, refinement and production of milk (and other agricultural commodities) has seen a massive consolidation wave in the last decades, giving these mega-corporations a massive amount of leverage over everyone else.
5. To protect their farmers, some countries have introduced price regulations (minimal prices) or tariffs, in addition to the subsidies.