Since CC0-1.0 was removed from the Fedora list of allowed code licenses, it would be nice if fedora-review would warn about it.

Sure, fedora-review cannot be certain whether the CC0-1.0 is used for code, but a warning should be fair enough if CC0-1.0 shows up in the license expression.

This came up during a package review: https://bugzilla.redhat.com/show_bug.cgi?id=2430713

See also:
https://docs.fedoraproject.org/en-US/legal/allowed-licenses/
Fedora to disallow CC0-licensed code, Posted July 25, 2022 by corbet
https://lwn.net/Articles/902410/

FWIW, license-validate doesn't warn about CC0-1.0 either:

$ license-validate -v 'CC0-1.0'                    
Approved license
$ rpm -q license-validate
license-validate-25-4.fc43.noarch