Have you checked it yourself to make sure it is nofollow? It could just be a bug with Ahrefs.
If it is nofollow, you can either talk to Namecheap support to see what the issue is, or just turn off the redirect, host the domain somewhere, and add a 301 redirect in the .htaccess file. That's what I would do to be sure it is done correctly.
If you don't know how to write the code for the .htaccess file, you can find plenty of examples online.