I corresponded with Puget Systems, who built my computer. Following their instructions, I was able to resolve this in two steps.
- Install 24H2, and see that Windows has been de-activated.
- On the activation page, click on "Change Product Key" and put in the OEM Activation code (found on the Microsoft authentication sticker on the back of my unit)
BTW, Puget says technically this is a result not of 24H2, but rather this October update: KB 5044285; That KB was an optional update which had never been installed, and was included as a "catch-up" update as part of the 24H2 package update.