

Mozilla started to test Firefox's Site Isolation feature in Firefox 70, and r olled it out in Firefox Nightly in September 2020. Uncheck "Use a background service to install updates".Scroll down to "Allow Firefox to" on the page.Load about:preferences in the Firefox address bar.

You may delete or disable the task, but it may be better to disable the option in the Firefox preferences. The agent runs through a task in the Windows Task Scheduler, called Firefox Background Update. Mozilla mentioned the feature in the Firefox 90 release notes, and it is unclear why it is mentioned again in the Firefox 94 release notes. On Windows, updates are now handled automatically in the background using a background agent. You can switch back at any time by enabling the theme again.

Note that the selection of a colorway will disable the active theme. There you find all available palettes, more than six, and the option to enable one of the available options in Firefox. These new palettes can also be selected on the themes customization page of the browser.
