A mongoc_client_t with automatic encryption (set via mongoc_client_enable_auto_encryption()) may use a separate inner mongoc_client_t passed via mongoc_auto_encryption_opts_set_keyvault_client to communicate with the key vault. Calling mongoc_client_reset should also reset the inner mongoc_client_t used to communicate with the key vault. Otherwise, the inner key vault client could end up reusing sessions from its own session pool.