I ran my test again and ran Get-Task without arguments after getting back "Success" on the specific task.

The relevant tasks are definitely still in the list.

Description                                              StartTime            FinishTime             State
-----------                                              ---------            ----------             -----
                                                         3/14/2023 6:49:02 PM 3/14/2023 6:53:40 PM Success
Deploy OVF template                                      3/14/2023 6:48:50 PM                      Running
Deploy OVF package from Content Library to Resource Pool 3/14/2023 6:48:44 PM                      Running
Delete virtual machine                                   3/14/2023 6:44:05 PM 3/14/2023 6:44:05 PM Success
Fetch Content of a Library Item                          3/14/2023 6:48:39 PM 3/14/2023 6:48:41 PM Success
Parse OVF package in Content Library                     3/14/2023 6:48:38 PM 3/14/2023 6:48:44 PM Success
Fetch Content of a Library Item                          3/14/2023 6:48:44 PM 3/14/2023 6:48:46 PM Success
Fetch Content of a Library Item                          3/14/2023 6:49:00 PM 3/14/2023 6:49:01 PM Success

In the full Task Console in the vCenter web UI, there are only four tasks that were a result of this New-VM, and they're all shown here: the "Parse OVF package…", "Deploy OVF package…", "Deploy OVF template", and "Transfer File(s)" tasks, the last of which is the one that has no description in this list. (Its "Name" is "NfcCopy_Task".)

So I don't think that it's a case of the tasks falling off the "recent" list.

Can you think of a reason that this would fail other than that the cmdlet is broken? I really want to open a VMware support case about this, but they're giving me a hard time about needing to purchase SDK support, but this feels very much like "Cmdlets are not working as documented".