At least Joao Felix has made some contributions to Barcelona and he is one of the players who is quite popular there, now he plays for AC Milan and that is his own desire, even there is desire to be able to really have permanent contract.
Felix has been popular before he joined Barcelona. He was one of important players in Atletico Madrid, he contributed well for Atletico Madrid. If he wasn't quite popular and did no contribution, Barcelona will never sign him.
Atletico Madrid and Chelsea are not the main purpose for Joao Felix, and Barcelona financial problems that made him have to leave have also been well accepted, now the most important thing is that Joao Felix can help AC Milan to compete until the end of the season in an effort to improve the standings.
He was likely having a problem with Atletico Madrid coach, so he was loaned to Barcelona. And after he failed to have a permanent contract with Barcelona, Chelsea signed him. Unfortunately Chelsea has too many players in attacking line, so Felix can't play regularly there. It is a better option to get a loan contract with AC Milan.