I was looking for documentation on exfat mount options (because my camera
seems to have no concept of timezones, which means it creates all files as
UTC, causing all file timestamps to be out by my local timezone offset) but
couldn't find any.

I assume documentation for all available in-kernel mount types belongs here?

Hello Michael Deegan,

* Michael Deegan <bugs@deegan.id.au> [211205 16:55]:

Its not that clear cut. man mount(8) documents filesystem specific
mount options as a favor to the user, but also says users should
look up details in the filesystem-specific documentation first.

Now it appears nobody ever wrote documentation on exfat, so there is
very little that can be included in the mount(8) man page.

Do you happen to have text that can be submitted upstream?

See https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/tree/README
for more info for making changes suitable for upstream, especially
about the signed-off-by requirements.

Best,
Chris