Since its last formal release, GNU Troff's git trunk has introduced a new macro, for encoding references to other man pages. man7.org/linux/man-pages appears to have imported some page sources, e.g. https://man7.org/linux/man-pages/man1/groff.1.html, which use this new macro, but your rendering engine does not support it; consequently, the displayed page is incomplete, and effectively unreadable in places.
man7.org is not affiliated with the Linux man-pages project. You will have more luck reporting at https://github.com/mkerrisk/man-pages/issues.
(In reply to Mingye Wang from comment #1) > man7.org is not affiliated with the Linux man-pages project. You will have > more luck reporting at https://github.com/mkerrisk/man-pages/issues. Strange then, that man7.org itself seems to direct here, for bug reporting; furthermore, that github repo, which has shown no developer activity in the last two years, requests that bug reports be directed here, and not to its issue tracker. Never mind. Michael apparently doesn't care that man7.org is poorly maintained, so why should I? Sorry to have troubled you.
>man7.org itself seems to direct here, for bug reporting Does it? https://man7.org/linux/man-pages/man1/groff.1.html#COLOPHON says: "If you discover any rendering problems in this HTML version of the page, [...] send a mail to man-pages@man7.org". (Though one could argue it's a groff bug...)
The github repository tells in various places (description, README) that it's just a mirror, and that the official repository and website are at <kernel.org>. Anyway, the bug report is for the HTML rendering in <man7.org>, so Jakub's comment is right, and you should direct your report to Michael at his email address. I'm not saying that he'll answer, though, as I didn't receive any answers to other reports from myself. :s Cheers, Alex