Links to <sup> do not work in PDF

In my test case, one has a QTextDocument with a footnote, i.e. ‘Foo ¹’ on top of the file and ‘1. some note’ at the bottom, and with link from the reference to the footnote and backwards.

When viewing this in a QTextBrowser, all is good, but when exporting to PDF, only one of the links works. It looks like link to <p> works, but link to <sup> does not.

I attached a C++ source file that generates a PDF, and the PDF file itself. I tested this PDF in Evince and Okular viewers.