GTK 4.18.3 is now available; this is a bug fix release of the stable branch of GTK, including fixes for Vulkan, accessibility, introspection annotations, HiDPI GL rendering on Windows, and macOS event handling.
You can read all the changes here: https://gitlab.gnome.org/GNOME/gtk/-/commit/a4033016969298dfedb5b96ae6fde41c332e3675
The main branch is now open for the next development cycle.