The headline change is the switch from paredit to smartparens' own default keybindings, fixing the long-standing conflict where M-s and M-? were shadowed by smartparens. Splice is now on M-D, and M-? is free for xref-find-references.
All language modules have been converted to use-package, and several modules received additional improvements (better LSP integration, updated packages, clearer comments).
See the full changelog for details.