Posi  filed an orphan request for btrbk :
this package is not updated a long time.
 https://aur.archlinux.org/account/Posi/  https://aur.archlinux.org/pkgbase/btrbk/
Request #27794 has been rejected by ainola :
Looks like it has been recently updated. Consider reaching out to the maintainer so you can get co-maintainer status to help out!