Not the end of the world for some of the players as they will still get to play for their national teams after the isolation period ends, but for Correia and Maxi they will not be able to represent their teams. Really bad for them and for Valencia CF as Maxi's international performances might have significantly increased his value in case VCF decides to sell him.
Thankfully Jose Luis Gaya has tested negative and will feature for Spain, so some good news in all this bad news. They are all asymptomatic as well, so no issues with their health at all, but a real bummer to have to miss international competition.