Hello @UlzzaG
Did you run gpupdate/force to reapplies all policy settings on all the desktops?
"Disables Automatic Updates through GPO does not block access to Windows Update." Quote from here: disable Windows updates via GP
You may also need to Prevent the Operating System from Being Updated Through Windows Update :
Click Computer Configuration> Administrative Templates> System> Internet Communication Management,> Internet Communication settings> Turn off access to all Windows Update features.
Reference article:
How to stop automatic updates on Windows 10
Best Regards
Karlie
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