Its one thing to decide you want to leave club suddenly, or that they dont want to play you, or want to sell you, that is part of the territory, contract doesnt mean you have to be there for its entirety. But when you are under contract, you have one basic obligation, you are available and ready to suit up, and they the club are obligated to pay you, wether you play or not. Under no circusmtances is it ok for you to decide you dont wanna play/be available when you are paid to be. Even if you ok with them punishing you with fines, its still absolute bullshit, even if the club are absolute assholes, train/be available, and do your job as a professional. I'm not sure why in the hell you are ok with this?
If Arthur did this in Juve, he would be the most hated figure around, its silly to defend this. I mean people called Iaquinta, Amauri, or currently Khedira "leeches", for not leaving simply because they past their used date, when they simply dont want to leave, are available with the contract they got. The true moronic leech is someone who is under contract and REFUSES to train/be available to play.
This is a huge red flag IMO.