When projects release a new version, they often include «release notes» with information about improvements, bug-fixes, and other changes. These projects are the best source of information about what has recently changed.
Below you’ll find links to the release notes for several major projects in the Jupyter ecosystem.
You can find a changelog at the Jupyter Notebook documentation.
You can find a changelog at the JupyterLab documentation.
You can find a list of changelogs in the JupyterHub community within the JupyterHub team compass documentation.