It IS in the agreement!
Prepare to feel embarrassed.
The claims Lavrov makes in the video you link are completely true.
Every ship that intends to carry grain out of Ukraine must be inspected in port to ensure it does not carry and deliver weapons.
Inspected in which port? A port in Turkey.
It’s clearly defined in the agreement.
Weapons don’t need to be sent to Ukraine on grain ships, and the grain shipments leaving Ukraine don’t belong to the Russians.