We also see this bug running do-release-upgrade on GCE base VMs.  Prior to running the upgrade and after running the upgrade, postfix is not installed:

catred@jammy-to-noble-upgrade-arm64:~$ dpkg --no-pager --list postfix
dpkg-query: no packages found matching postfix


If I create a second SSH shell during the upgrade while paused on the postfix prompt, I see:

catred@jammy-to-noble-upgrade-base-amd64:~$ dpkg --no-pager --list postfix
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name           Version      Architecture Description
+++-==============-============-============-=================================
un  postfix        <none>       <none>       (no description available)





The prompt I get is:

Package configuration                                                           
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
  ┌────────────────────────┤ Postfix Configuration ├────────────────────────┐   
  │ Please select the mail server configuration type that best meets your   │   
  │ needs.                                                                  │   
  │                                                                         │   
  │  No configuration:                                                      │   
  │   Should be chosen to leave the current configuration unchanged.        │   
  │  Internet site:                                                         │   
  │   Mail is sent and received directly using SMTP.                        │   
  │  Internet with smarthost:                                               │   
  │   Mail is received directly using SMTP or by running a utility such     │   
  │   as fetchmail. Outgoing mail is sent using a smarthost.                │   
  │  Satellite system:                                                      │   
  │   All mail is sent to another machine, called a 'smarthost', for        │   
  │   delivery.                                                             │   
  │  Local only:                                                            │   
  │   The only delivered mail is the mail for local users. There is no      │   
  │   network.                                                              │   
  │                                                                         │   
  │ General mail configuration type:                                        │   
  │                                                                         │   
  │                        No configuration                                 │   
  │                        Internet Site                                    │   
  │                        Internet with smarthost                          │   
  │                        Satellite system                                 │   
  │                        Local only                                       │   
  │                                                                         │   
  │                                                                         │   
  │                   <Ok>                       <Cancel>                   │   
  │                                                                         │   
  └─────────────────────────────────────────────────────────────────────────┘