When a user uses creates a mongoc_client_t via a URI that specifies values via TXT record, the URI stored on the mongoc_client_t is not updated according to the records – per this line in the DNS tests it appears only the topology's copy is.

Since the topology is not publicly accessible, this makes it impossible for the Swift driver to e.g. get an accurate picture of the options set on a URI or to fully implement the initial DNS seedlist discovery spec tests.