The Special:Thanks/xxxxx page is sometimes seen if an editor clicked the "Thank" link, before the relevant JavaScript had finished loading.
(It can also be seen if the editor is not using JavaScript at all (either voluntarily, or because they're using an old or incompatible browser). But usually the first.)
There are similar cases (for identical reasons - clicking too fast) with the Watchlist stars/tabs, and the Notifications badges.
However this case is a problem, because it doesn't take the editor back to a useful destination. They would have to click [Back] twice in their browser.
Here are the steps, which can easily be reproduced just by clicking "Thank" as soon as it is visible (without waiting for the page to finish loading)
Instead, we should link to the page where the "thank" link was originally clicked on, so that the editor can navigate back there. (The primary intent of this page is for non-JavaScript users. It is only accidentally encountered by other users).