Neymar is a really great player, as is Mbappe, but their vanities are huge and it is obvious that the PSG team can't have two leaders.
PSG tried to elegantly solve this problem and get rid of Neymar, but they failed because other clubs know very well what they get with Neymar, as an additional package.
PSG has a great and very expensive team, but if they don't solve the problem between Mbappe and Neymar, they won't fulfill their main goal again, winning the Champions League.
I would not call this a problem between Neymar and Mbappe (although formally it is), the main problem is Mbappe, who fell ill with star disease and requires special attitude and additional privileges. PSG bosses themselves are to blame for this situation, since in any top club (and especially in such a money bag as PSG) there will always be more than 1 star, which means you need to select players so that they can work together without conflict.
It is obvious that Neymar is a great player. However, it is also obvious that big teams are not going to be interested in signing him. They are concerned that if they get Neymar now, they will not be sure if they will get a good deal from the player as well as if the player will be able to perform well for them!
On the other hand, Neymar can also perform well under pressure. It is still a great pleasure to watch him play. The only question now is whether he will be able to continue his good performance on the new team as he did before? Furthermore, if a team gets Neymar right now, they will also have to keep in mind that in order to get him, they will have to pay him a very good amount of salary. My thought is that if any team is willing to pay that much salary, then they have other better options, younger and better, that they have the option to choose from.