This is now a Rust package, hence it only builds on %{rust_arches}

No real difference for Fedora or modern RHEL, but the guidelines say so:

https://docs.fedoraproject.org/en-US/packaging-guidelines/Rust/#_exclusivearch

python-cryptography.spec

@@ -25,6 +25,8 @@ Source3:        cryptography-%{version}-vendor.tar.bz2
 Source4:        conftest-skipper.py
 %endif
 
+ExclusiveArch:  %{rust_arches}
+
 BuildRequires:  openssl-devel
 BuildRequires:  gcc
 BuildRequires:  gnupg2