When an old notification is clicked then an error is displayed 'The version XXXXXXX is not a draft'.

So the approach I was thinking is that we maintain notification status and visually differentiate between New, Pending Review (this is when the request has been viewed), and Publish notifications. If the object has been published then we can just link it to the published version or maybe remove the link.

Based on your input and proposed approach - I can design and write down the reqs.