never seen the fans not one of neymar's standard to come to barca. even griez was meant with lesser resistance. says a lot about how these past two seasons at psg have tarnished his legacy. even real madrid fans seemed averse to signing him even before hazard joined. poor guy
What have tarnished his reputation are his two long term injuries and the mess of his WC where memes were made out of him. The World Cup has been more detrimental for him than PSG because he had turned onto a laughing stock for the casual watchers and be more hated by the regular fans.
What PSG switch has made is that people watch less matches of Neymar. They will watch some of his CL games and he was injured after the group stage. So people keep in mind his WC and everything negative about him. If people were actually watching him regularly, they would have seen he has been pretty brilliant before his injuries. The guy average almost 1 goal per game and 1 assist per 2 games. Even in CL, he has scored quite a few goals and played well.
What a Barça switch would do is people watching him play regularly again. When they'll see how good he is, they'll say that he needed to come back to Barça to recover his level (that he has lost when going to PSG). It is just perception at this point.
Real Madrid fans want Mbappé. He has not played for Barça before and is very young. I can understand why they want him over Neymar. However, if you forget Neymar baggages and assuming he doesn't get long term injuries again, Neymar is on a whole other level than Mbappé at the moment. So, if someone tells you they don't want Neymar because he has become shit at PSG but they want Mbappé because he is already better than Neymar, you can already tell this person didn't watch PSG at all. Even in CL, Mbappé has been quite disappointing considering his status. Neymar has stepped up.