(For those unfamiliar with Emacs versioning, 31.1 is what would be called 31.0 in a more typical versioning scheme)

There are a large number of changes in Emacs 31:

- https://git.savannah.gnu.org/cgit/emacs.git/tree/etc/NEWS?h=...

- (mirror) https://raw.githubusercontent.com/emacs-mirror/emacs/refs/ta...

Maybe someone will write an article/post summarising some more notable changes! There was already this one previously: https://news.ycombinator.com/item?id=48584135