Create a new branch 2.2.x so we can drop D9 support, raise the minimum core version to Drupal 10.3 and start adding Drupal 11 support.
2.1.x will continue to work for Drupal 9.2+ up through and including Drupal 10.2.
There are many breaking changes in Drupal core that make it difficult to support D9, D10.2 and D10.3 in the same codebase without a lot of conditional code. That is why I've decided to put all the changes into the new branch and leave the old branch for "legacy" sites.
Fixed
2.2
Code