Review test in CID retirement section

[mirjak]

The list of received packets used to send acknowledgements also remains unaffected as the packet number space is associated with a path.

and

The peer, that sends the MP_RETIRE_CONNECTION_ID frame, can keep sending data using the same IP addresses and UDP ports previously associated with that connection ID, but has to use a different connection ID when doing so.

These are just plain RFC 9000 behavior and might not be mentioned here explicitly.