If the user already has access to the list item which has unique permission, then "Grant Access to an Item or Folder" step will not add the user to the unique permission

Question

We have a case where some users are defined as site collection admins inside a SharePoint online site >> and we define a workflow which Stop Permission inheritance + ONLY grant the createdby user Contribute on the item, as follow:-

now in case the createdby user is defined as a site collection admin >> then the above Action of granting permission to a list item will not add the user to the item unique permission ! this will/might cause an issue in the future, becuase if the user is removed from the site admin settings, then he will lose access to the items he created. is there anyway to fix this?

Second question; If i grant the access using HTTP Request instead of using the "Grant Access to an item or folder" will it fix the issue? i know that MS flow integrate with SharePoint using HTTP requests rest API.. so is our problem a limitation on the SharePoint Rest API or in the Power automates "Grant access to an item or folder" step?

Thanks