Here is what you do, go to google, type in elitepvpers, go to forums, navigate to the Fifa forums in the Other Online Games section, pick and choose your own FIFA trainers that disables disconnect on focus loss.
I know for a fact there are a lot of you out there who are not computer savy and have something else that's causing the focus loss. This is a solution for you.
I know it's installing a cheat application, however at this point it's the only way for you to experience part of a game that you paid for. Also if you want to use the other functions that's entirely up to you. My opinion on that is the only way for EA to care is if they are losing money. More cheaters = more frustrated non-cheaters who might not buy the game next year.
If enough people stopped buying the game maybe in FIFA 22 we'll get a game that has an anti-cheat protection that's not something from the 90s aka alt tab focus loss disconnect.