As explained in [1], there actually are conventions for writing man pages given in 'man 7 man-pages'. Thus .TH line can be trusted to contain the date of last non-trivial change:
date: The date of the last nontrivial change that was made to the man page. (Within the man-pages project, the necessary updates to these timestamps are handled automatically by scripts, so there is no need to manually update them as part of a patch.) Dates should be written in the form YYYY-MM-DD. [1] https://lists.debian.org/debian-devel/2021/02/msg00040.html Andrius
