Problem
Currently, the infobox on Special:Contributions looks up the revision of the top entry on the page. If you change pages, the top entry of the page will be different and so the revision looked up by the infobox will be different.
If a temporary user is using different IPs, the data shown by the infobox might change per page.
Example
From my local environment, somewhat unrealistic because I have set the number of entries per page to 1, but the same principle applies for a larger limit.
First page of Special:Contributions:
Second page, IP information is different:

