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.
When you put yourself in Joaoh Felix's shoes, you will not be a happy player as well because no credible club was interested in having him in their team after his failed transfer to Chelsea, because prior to his move from Atletico Madrid to Chelsea, so many fans had high expectations from him and things went south, and that coming back to the club has not bee yield for him but if indeed as you said that Barcelona is having interested in him, it will be a stepping stone for him and easy path to regurgitate his career but Manchester United is the least place Erik will tolerate, they already had good attackers and I don't think there is an available fund to buy him.