SyncMadeEasy/force-app/main/default/classes/UpdateCustomerFromShopifyAuthentication.cls

@RestResource(urlMapping='/UpdateCustomerFromShopifyAuthentication/*')
global with sharing class UpdateCustomerFromShopifyAuthentication {
    
    @HttpPost
    global static void updateCustomerWithAuthentication(){      
        //Deprecated
       //Class no longer exists   
    }      
}