What’s Changing 
Starting the week of September 4, 2023, MerchantLinkService.MutateMerchantCenterLink  method will fail with an AuthorizationError.ACTION_NOT_PERMITTED  error for authorized users without Admin access levels. 
Required Actions 
If your application mutates Merchant Center links using the MutateMerchantCenterLink  method, review the account permissions of the users authorizing API calls and update their permissions appropriately to ensure they have the required access levels. Refer to the help center guide  for instructions.
Change Rationale 
This change will align the Google Ads API behavior with other products such as the Google Ads UI and Google Ads Editor, which only allow Administrator users to mutate Merchant Center links. Currently, the Google Ads API allows users with Standard Access levels  but without Admin access level permissions to mutate Merchant Center links  using the MerchantLinkService .
If you have any questions, please reach out to us on the forum .
Anash P. Oommen , Google Ads API Team