The change stream specification test plan says:

The killCursors command sent during the “Resume Process” must not be allowed to throw an exception

This was not properly implemented in the driver. In particular, if the attempt to get a connection on which to send the killCursors commands results in a ConnectException, then that exception will be thrown instead of being suppressed. As a result, if the attempt to kill the cursor fails (as when the server with the cursor is shut down) then the driver will not properly resume the change stream cursor and instead throw the exception.