You’re doing it again.

As a publisher: Yes, Epic stopped the Rocket League devs from continuing to build Linux binaries. To my knowledge, they have not disabled “support” for Proton in any of the anti-cheat solutions.

Similarly, the development branch of CD Projekt (the parent company of GoG), apparently had Linux binaries for The Witcher 2. They do not for The Witcher 3 or Cyberpunk.

Both companies decided it was not worth internally supporting Linux and instead rely on Proton/Wine to do it for them. Whether that is good for gaming is debatable, but both are “actively hostile towards Linux” in that regard.