Ipfs unpin updation in dht

I am building an application using Ipfs .
It involves transfer of files between systems through Ipfs . When a file is transferred from peer A to peer B , peer A unpins and perform repo gc after transferring the file to B . Now Peer B need to confirm that A has unpinned and performed garbage collection.
This I was attempting to do using Ipfs dht findprovs .
But this still return A’s peer ID as content provider even after A unpin and perform reap gc .

Is there any way to make sure that user A has unpinned or not ?

Other than ask it and trust that it’s telling you the truth? No.