Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
flatted is used as part of the vscode plugin for rust-analyzer, for testing of the stringdex crate, and building documentation for the cxx crate. The vscode plugin isn't packaged with rust-analyzer, stringdex tests are not shipped, and the cxx crate isn't built under the fedora configuration. So, this shouldn't affect users of the rust package.