Before the war Agriculture made up 12.2 % of Ukraines GDP. With the widespread destruction by Russia, it is probably up to something around 40%. From the 68 Billion $ export in 2021, 23 Billion were Agricultural goods. Now with the widespread destruction of the Ukrainian industry, Agricultural products make up probably more like 80% of the export.

This grain ban is tying the noose around the neck of Ukraine. Also the argument is interesting. Ukraine argues, that it needs to pass its products through Poland and the other countries to sell it on the world market. But in Poland and the other countries some of it gets diverted to be sold on the local market. So who is doing the diversion? The Ukrainians, or some local company seeking a quick profit?

Poland and the others could easily prevent the diversion of Ukrainian grain. Well they could if they werent corrupted to the core (Poland and Hungary).

Orban has been chilling for Putin and China quite extensively, but the PiS government doesnt care, because they align on reactionary social policies and corruption with Orbans Fidesz party. The criticism by Zelensky is justified, both from the fact that what remains of Ukraines economy is getting strangled, as well as the fact that this is benefiting Moscow and at least Orban wanting exactly that.

Wiki-Economy of Ukraine