Not sure, but they were able to get Wayland support working out of the box in this update. Previously it required workarounds, and even with workarounds, new issues would pop up in a game of whack-a-mole, and nobody really cared because running MC in XWayland was good enough for most people. Whereas SDL3 has very solid Wayland support out of the box. Minecraft only really uses GLFW to create the window, set the taskbar icon, go into fullscreen mode, and accept input, with everything else being handled by raw OpenGL, so this was an easy switchover. Now that Minecraft supports Vulkan, it's able to use a fully modern stack on Linux desktops / Steam Decks.