Hi,
I noticed that this commit:
b1a570b3b  org-agenda: Fix regression when diary sexp timestamps are ignored

made a call like (org-at-timestamp-p 'agenda) match against the regexp
`org-element--timestamp-regexp`. However, this regexp doesn’t have the
match groups setup as the others (`org-ts-regexp3` and `org-ts-regexp2`) so
the last part of the docstring for org-at-timestamp-p doesn’t hold anymore
(that the timestamp parts should now be put in match groups).

I was using this in some code of mine, but I also realize that this doesn’t
feel all that clean anyway. I am not sure if this is used elsewhere in org
though.

Best,
Anders