Updates are resetting my power settings in Windows.

I do not think the updater interacts with the operating system at that level to cause the effect you are observing. Operating system interactions are few in the Mozilla platform as the actual operating system the code runs on varies a lot. Windows, Mac OS, Linux etc.

You could try disabling the use of a background task in settings to see if that affects any sort of change, but I do not hold out much hope. The silent update is documented here https://wiki.mozilla.org/Windows_Service_Silent_Update

Are you also using Firefox? it has an updater that can update when the application is not open using the windows task scheduler, and that task could prevent windows going to sleep, or even wake the system to do the task I assume, but I don't see it changing the settings.

Thank you. I am using Firefox but I only notice the changes to settings when Thunderbird or (in my wife's case) EM Client are updated, but just because I don't notice it doesn't mean it isn't happening elsewhere.

I will eventually have to upgrade to W11 but current machines aren't capable and two new ones aren't in the budget at the moment. I suspect the problem will go away with the upgrade. Thanks for the response.