The Mutter 3.23.91 release does have a few interesting changes including edge-scrolling without 2-finger-scroll capable devices, full-screen windows now appear on the requested monitor on Wayland, a threaded swap event fallback for the NVIDIA driver, and other fixes. Most of the GNOME core and apps changes though for this v3.23.91 release mostly come down to fixes.
More details on GNOME 3.24 Beta 2 via the release announcement. The GNOME 3.24 Release Candidate is set for 15 March while the official release is expected on 22 March.
See our past GNOME 3.24 articles for more details on the feature work this cycle; I'll provide a proper feature overview in the next week or two.