Org Mode is maintained as a separate project, and is periodically
merged into Emacs.  To view or participate in Org Mode development,
please go to https://orgmode.org/ and follow the instructions there.

The source code from the upstream Org Mode project is usually not
identical to the version of Org Mode in Emacs.  The upstream project
often has recent changes that have not yet been merged into Emacs, and
Emacs sometimes has local changes to Org Mode that have not yet been
backported to upstream (https://orgmode.org/worg/org-maintenance.html
documents how the Org Mode project synchronizes changes with Emacs).

Thus, if you're investigating a bug you encountered in Org Mode in
Emacs, you should obtain the latest upstream code and see if the bug
is present there.  If the bug is present, then the upstream Org Mode
project is the proper place to fix it.  If the bug is not present
there, that could be because it has already been fixed upstream, or it
could be because the bug was only introduced on the Emacs side and has
not yet been backported upstream.  Either way, this is something you
will need to know in order to know where to contribute your fix.