When viewing a migrated question, a banner appears with a link to the revision list of the question at its original location. Hovering over it does not really provide new information: it's the title of the question as it appears in the URL:
This even leads to unreadable tooltips for Russian questions like this one:
The New Post Notices rollout on Stack Overflow didn't get rid of this 'feature', see this example (if your browser is in the test group):
Do you have any thoughts as to what would be useful information for this tooltip? The title isn't particularly useful as the current title is shown on the page already. If there are no good suggestions, I propose we get rid of the tooltip altogether.