Hello, i'm a Galatasaray supporter who also watched Leicester games for the last 2 years. For anyone asking why GS accepted such a loan, it is because we have a deal with the banks, half of GS income this year is taken by them. So not only Yunus but also a bigger player like Zaniolo was sold with similar options.
Yunus was a promising young winger, he played good at Adana before returning to GS. His weakness is his decision making and i don't think he is quick enough to play at Premiere League but he probably will be ok for championship. He would be more successful at Italy or Spain where the game is slower. He became 4th option after Tete, Ziyech and another Turkish player so that is why GS is selling him.