MarsSeed [1] filed a deletion request for u2fval [2]:
Legacy package, last updated in 2017.
Last code commit was also in 2017. [a]
Since Aug 2020, the project readme says:
"This project is no longer actively maintained." [b]
[a]: https://github.com/Yubico/u2fval/commits/master
[b]: https://github.com/Yubico/u2fval#readme
So I think this package should be deleted.
[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/u2fval/