He’s on a late minute loan move to Galatasaray. The choice was go on loan to Turkiye or spend the season (at least until January) not playing.
He’s on a large salary at Napoli. After being a key component in winning the league title, he wanted a move away to a bigger side. Throughout the season he was doing little bait and hints about wanting bigger and better things, similarly the Napoli chairman is a bit of a mentalist wanker who wasn’t happy with that. I think he had links to Chelsea deep into the summer, but the move never materialised. At that point it was too late for another big club to pay the big transfer fee + match his salary demands. Hence the panic move to Turkiye on loan (where, as mentioned in this thread, salary tax is lower hence easier move along).
He is now linked with a move “in his prime to us or another big club”.