The changeset in 3.2.1 is predominently added async integration tests. Those tests should now be replicating all the logic in the good old sync integration tests under test_caldav.py. Some few more bugs were found while adding those tests.
There are two "feature commits" adding new parameters to existing functions. Those are minor additions and was required while fixing things (test breakage plus observed crash due to weird real-world-data), hence I define this to be a patch-release rather than a minor-release.