To all the people saying they should release server source code: You don't even need to do that (as nice as it would be). At the very basic level all that is needed is:
remove DRM (which probably cost more effort to add in the first place)
a description of the API for any online components (which any decent dev team will already have internally documented)
remove DRM (which probably cost more effort to add in the first place)
Denuvo charges monthly. And, looking at history of games, takes no effort by developers. Heck, they even can take their own pirated game with DRM removed. And even if removing DRM costs money, they have nobodu, but themselves to blame.