Osimhen is undoubtedly a top star and it is safe to say that he will leave his current club to join another club in Europe but €130 million is too much for him. He may be a very good player but no club in Europe will spend 130 million euros to sign him right now. If Napoli agree to release him from 100 million to less than 100 million, maybe his change of club will be faster. A player like Harry Kane signed to Bayern Munich for €110 million plus, no club would buy him for €130 million. He can be transferred for a maximum of 110 million euros, but he may not be transferred for more than that.
He used to be a very good player but his performance has dropped and I can't imagine that any club would be willing to pay >100 million € for him. A sum under 100 million € seems more likely to me and if Napoli want to sell him then they will have to lower the price a bit. It would be a big surprise for me if someone would buy him at the current price.
I don't think his form has dropped that much, I just feel its because of how Napoli failed to play together as a team, osimien is a very good player and with the way the transfer market has turned out 100 million for osimien isn't actually a bad price beside they are far less price that are worth that price that clubs still buy.