The module on the forge is not current with what is here on Github, despite the version being the same in metadata.
Also the version on the forge fails to install as the dependency for nftables is incorrect, referencing puppetlabs instead of puppet (vox pupuli). The version is also too low, with an upper limit of <2.0.0 (it is now at v2.1.0)
Can you please update the metadata as below and publish the current github copy to the forge?
{ "name": "puppet/nftables", "version_requirement": ">= 2.0.0 < 3.0.0" },