That's the main problem of the country but if you look it more, the causes stretched more than that.

Nigeria is divided by different ethics and regions of different states, there are North, North central, Southeast, Soutwest region. The only place that where farming activities takes place is the North and the North Central where agricultural farming take place and this region because of high level of poverty and low education, some group of people recruit there children into banditary to disturb people from farming. This insecurity has chase away farmers from going to the farm and this has resulted into low farm produce and because of demand, the local farmers can't meet up with the demand which has made the available ones to be expensive and the government has also closed the borders, there has not been a way for people to import goods from other countries.

Subsidy removal: On the may of 23, 2023, the new government came into power and remove subsidy from fuel, so technically everything became expensive, the farmers depend on fuel to make their farming easier from hiring tractors to make ridges, processing their harvest into final foods and cost of transport from farm to their respective house storage where their produce are store. This is why food is very expensive for ordinary people to buy.

Increase in Inflation: The harsh policy set up by the new government has made everything so expensive, you can't even differenciate the price between locally produce items to the ones they are selling outside but because borders are close, it's impossible to bring in some items. Some people are even saying that the cost of buying some items from outside the country is cheaper than buying within the country. This is the mess we are right now and the problems is from failed governments who love looting from the day independence was given to the country.