There are two problems. The Polish government directed their farmers to increase output before this happened. And the Ukrainian grain that isn’t allowed to be sold in Poland anyway (they adhere to EU minimum food standards, so they are not allowed to use Ukrainian grain in food production (it’s produced for example with cheaper fertilizers and pesticides banned in the EU)) is finding it’s way into Polish markets -illegally that is- and crashed the price.

They could address their issue about corruption and effective EU laws about food safety getting broken… or they could create a general ban (basically make something illegal that isn’t legal in the first place) and spin a story about bravely defending their farmers from the EU (…from getting fucked over by their own corruption actually - but don’t say that quiet part out loud).

It’s election time and they are populists running on anti-EU narratives. So option 2 it is.

PS: Ukraine’s government is also not blame-free here. Their grain should be transported through Poland, not be sold in Poland. So the public push back against a ban that isn’t affecting that (transit is still allowed), should not generate such a reaction. They are either just stupidly over-reacting or -and that case would be even worse- complaining that they are not allowed to exploit Poland’s internal problems to sell their grain there directly. Which is of course easier for them… but that was never the intention when allowing the transport of Ukrainian grain.