The upstream download site for the cudd package stopped responding about 8 months ago. About 4 months ago, the DNS entry for the upstream download site disappeared. Strangely, the author's home page still has a link pointing to that site.
In any case, nothing in Fedora uses cudd anymore. The cbmc package still has a BuildRequires for cudd-devel, but doesn't appear to actually use it. I intend to drop the BR from cbmc and retire cudd in F31 and Rawhide at the end of this week.
If anybody wants to keep it, let me know.