JupyterHub 5 is out now, which you can get with:
pip install --upgrade jupyterhub
it will roll out to conda-forge shortly.
This is a major release because some defaults have changed, the minimum Python version is raised to 3.8, and it requires a database upgrade, but hopefully not a too-disruptive version to upgrade to.
JupyterHub 5 introduces user-initiated sharing and authenticator-managed roles
Check out the new migration documentation and the changelog for more details.
Give it a test, especially the new features if you can, and let us know how it goes.
Thanks to everyone who has contributed, especially feedback from prerelease testing.