At time-of-writing, about 500 sites use the 4.0.x version of this module, but it doesn't have a stable release covered by security advisories.
Let's make a stable 4.0.0 release, marking it as "Supported" and "Recommended", and opting into security advisory coverage.
Determine what we need to do to get a stable release of this module, then do those things!
Some issues that would be nice-to-have for a release, but aren't technically blockers are...
Some issues that we need more information from participants are...
Other issues that are Open Bug reports and Tasks filed against 4.0.x-dev → , which the maintainers do not consider to be blockers are...
Active
4.0
Code
I've moved the D11-compatibility issue to be a non-blocker: see #3429173-9: Automated Drupal 11 compatibility fixes for ckeditor_abbreviation → for more information about why.
(Marking off the task to look through the open issues)
(I'm editing the issue so d.o rebuilds caches for this page and updates the issue link backgrounds to indicate the status)