MarsSeed [1] filed a deletion request for par2cmdline-tbb [2]: Fork discontinued in 2015. Repo version of par2cmdline provides the latest release from 2020 and is using OpenMP for parallel processing. Therefore I don't think this very old alternative multithreading version of par2 is needed anymore.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/par2cmdline-tbb/
