I don't know how true this is... But if it is then it would be the reasonable thing to do for Sporting. Because there is no way they are selling him for a price like 85 million pounds (~100 million euros).
His market value is 75 million euros according to Transfermarkt. They should be more reasonable with the price. He is a great striker but expecting 100 million for him is too exaggerated.
It is very surprised if Sporting really drops the price of Viktor Gyökeres to below €60m. This striker is targeted by some big teams, ideally Sporting keeps his price around €75m at least. I'm sure Arsenal still wants to sign him above €70m. But if Sporting is ready to accept the price below €60m, I assume Arsenal will sign him as quick as possible. We know that Arsenal is in a crisis of a striker, they are in urgent for a new striker. Viktor Gyökeres looks very suitable player for that position now.
Anyway, there is no offer from Man United for Viktor Gyökeres?