The Inspector doesn’t provide that info, because what it displays is the dynamic DOM structure and not the original HTML source sent over the wire. Also, HTML is normally generated on the server side and there is no source mapping between the server-side scripts and the DOM.
To get to know where the attributes come from, you should first use the newly added full text search of the Network panel to search for the words.
If you know they get added via JavaScript, you can use the also recently added DOM mutation breakpoints. Those allow you to stop the JavaScript execution right where the attributes get changed.
Sebastian