Gregory's Server
Mastodon now supports automatic switching between the light and dark theme, depending on your system setting.
It will be available in the upcoming 4.3 version, or is already there if your instance runs the nightly code.
You can switch to this new automatic theme in your Appearance preferences. Instance admins can also set it as the default theme (I just did it on mastodon.social and mastodon.online).
This has been done in https://github.com/mastodon/mastodon/pull/29748, thanks a lot to @nshki for the initial PR!
Another recently merged feature is the new "severed relationship" notifications. Those will appear when a moderator or admin blocks a user or a whole domain and this action caused you to loose some follows or followers.
Those blocks used to be invisible to users, you maybe saw your follows/followers count decrease but nothing more. Now you can access a list of those blocks, and download a CSV file with the list of impacted accounts.