Support to OBv2.1 was added in
MDL-66992 for Moodle 3.9. However, it was one of the first implementation of this specification and there were no certification process for that.
Since then, some early adopters have been working on their OBv2.1 implementations and that has helped to test Moodle implementation.
This issue is the epic to collect all the changes required to make Moodle OBv2.1 compliant and fix missing/wrong points.