Not sure that there's a GPO setting to kill it yet, though you can do it via Settings.

Err, not Settings, but right-clicking on the Taskbar and going to Search

Ah, you can kill it via the registry: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Feeds\DSB ShowDynamicContent = 0

Hmm, wait, that may not be the trigger.

This also changes: [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\SearchSettings] "SafeSearchMode"=dword:00000001 "IsDynamicSearchBoxEnabled"=dword:00000000 So maybe both are needed, and require a logoff (unless it applies before explorer.exe runs?)

Better yet, it's available via ADMX: https://www.microsoft.com/download/details.aspx?id=104042

"Allow search highlights" setting

Thanks for this, gonna shut that nonsense off right now.