Erdogan as a liaison measure. Why US and EU use the Turkish President to contact Putin
Secondly, Erdogan played the role of a mediator in this history, not the subject of negotiations on a grain agreement. The decision to weaken sanctions against the Russian Federation as a compromise for the restoration of the grain treaty should be made not in Turkey or the UN, but in the EU and the US, and it is Putin through Ankara. Third, Erdogan is obviously preferred by the variant of the grain agreement that was.
Judging by his words, Turkey acts either for returning to the status quo or for expanding the agreement at the expense of participants and the nomenclature of goods. But this requires a compromise, and Erdogan played the role of messenger here, offering alternatives, agreeing them with Moscow, then with Washington/Brussels. The creation of corridors without Russia does not support Turkey, and Erdogan clearly stated it.