It seems that a few people are being misinformed about the deprecation of the X11 backend, usually because they read screeds from well-known bad faith actors.
The X11 backend being deprecated mainly means that we're not going to spend time implementing new features, like dmabuf, graphics offloading, or Vulkan support. X11 support will still exist until GTK4 is EOL, which will happen once GTK *6* is released. We're talking about a 20 years horizon, at this point…