KDE Plasma 6.4 ships with continued enhancements to its Wayland support, splits off the KWin X11 code for better segregation from the increasing Wayland-first focus, various performance enhancements, better drawing tablet support, more work on HDR / color management, a better notifications experience, a nicer System Monitor app, and many other desktop refinements and bug fixes throughout. There is a heck of a lot of new features and other changes in Plasma 6.4 for further refining the Plasma 6 desktop experience.
More details and screenshots on the great work that has gone into Plasma 6.4 via KDE.org .