MarsSeed [1] filed a deletion request for python2-bibtexparser [2]:

Broken Py2 package: missing a Py2 depend.

But it is only optionally required, by one package. But that one is
already on Py3, so it needs to change to using python-bibtexparser,
available on AUR.

Safe to delete this defunct one.

[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/python2-bibtexparser/