Felix needs to play regularly to bring back his work off and on the ball again. He looked so lazy af when he played, and i think Conceição can pressure him. His team lost against Feyenoord, but it seems he's improved by seeing his game play. He only having very low work rate work on and off the ball.
As long as he can increase it, he's good.
No matter how great a player is, if they don't get much playing time, their performance will decline. What Felix has to do is he has to be able to get a main position and be able to play more regularly in order to restore his performance. The only thing he can do is keep training tirelessly to gain more trust from the coach. He is still young, and at his young age he has played in several big clubs and that should give him good experience and to make his performance better than before. He can do anything, as long as he has a strong desire to do it.
Of course, there is still room for improvement for the Portuguese player. It is up to him to continue his development. He made a lot of noise in the world football market when he was transferred to Atletico Madrid. Because Atletico Madrid paid a very high transfer fee for this transfer. However, Joao Felix could not show a performance that would be worth this transfer fee. Considering the situation we are in, we can say that Milan is now the last door for him in the big teams. If he cannot be successful here, he can probably make one of the Saudi Arabia transfers.