muvori [1] filed a request to merge protonmail-desktop [2] into
protonmail-desktop-unofficial [3]:

Seems to be the same package, but actually maintained.

[1] https://aur.archlinux.org/account/muvori/
[2] https://aur.archlinux.org/pkgbase/protonmail-desktop/
[3] https://aur.archlinux.org/pkgbase/protonmail-desktop-unofficial/