It seems that Joao Felix's return to Atletico Madrid did not make him Happy. It seems that he still can't get in touch with Diego Simeone. With these bad rumors, Joao Felix has been linked with many clubs wanting him. I think Joao Felix is a good player, at Chelsea he was not at his maximum because of the coach. There is news Barcelona and Man United are interested in Atletico's most expensive player. Of course they can take advantage of this bad moment to get Joao Felix.
Even though Joao Felix was very comfortable playing at Chelsea, he was not made permanent by Chelsea and had to be willing to return to Atletico after his loan period ended. Joao Felix is a good player, he can fill several positions such as AMF, SS, or LWF, it's just that the team that accommodates him is not so able to take advantage of his talent.
If it is true that the current situation with Atletico is getting worse, it is likely that he will leave if there is an offer from the English team, but considering the cost, it is certainly not cheap for a player like Joao Felix. At present his market value is 50 million euros and it is possible that the transfer fee could be more than that considering that Atletico first brought him from Benfica for a total fee of 127 million euros. I don't think either barcelona or manchester united will be able to afford it.