The package rpms/firefox.git has added or updated architecture specific content in its spec file (ExclusiveArch/ExcludeArch or %ifarch/%ifnarch) in commit(s): http://pkgs.fedoraproject.org/cgit/rpms/firefox.git/commit/?id=4070ba4d8b07c....
Change: +ExcludeArch: armv7hl aarch64
Thanks.