Hello @Fahrid F
This may be a code issue not yet detected. Same happened in 1803 (v1) back in the day: https://learn.microsoft.com/en-us/troubleshoot/windows-client/group-policy/resource-stringid-win7only-not-found
For a deeper troubleshooting in case you doubt your environment would be to rebuild the policy repository
** first of all take a backup of whatever is in your shared repository in the DC, for safety
With the Group Policy management console closed (it always should be closed when updating templates):
Rename "PolicyDefinitions" in your \Windows\SYSVOL\sysvol\DOMAIN\Policies folder to "PolicyDefinitions-Old"
Create a new "PolicyDefinitions" folder in the same location
Copy all the new ADMX/ADML files into their proper places on that DC.
Open Group Policy management again and see if things are back to normal.
Hope this helps with your query,
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