This is from our wonderful community coordinator – Wilma Hodges. I just pasted it into a blog post for the record.
I’m pleased to announce that Sakai 21.0 is now available!
Many thanks to everyone involved with the release! It wouldn’t happen without all of you!
Our community wiki has both functional  and technical  release notes.
Download instructions are also available .
New in Sakai 21
- Dark Mode
- Dashboard – New tool!
- Lessons improvements, such as revamped Add/Edit Dialog, new Add Layout template options, improved Reorder and Date Release Indicators, and more color and formatting options for headings, buttons, and borders.
- LTI Advantage Improvements, including autoconfigure option and new LTI Assignment Type in the Assignments tool.
- Gradebook enhancements for exporting category averages and messaging students from the gradebook
- Rubrics are now searchable and can contain weighted criteria
And more! 
 Functional release notes – https://confluence.sakaiproject.org/display/DOC/Sakai+21+Release+Notes
 Technical Release notes – https://confluence.sakaiproject.org/display/DOC/Sakai+21+Technical+Release+Notes
 Download instructions – http://source.sakaiproject.org/release/21.0/
 Complete Feature Summary – https://confluence.sakaiproject.org/display/DOC/Sakai+21.0+Complete+Feature+Summary
Wilma Hodges, Ed.D.
Sakai PMC – Community Coordinator