Supabase has introduced custom domains and vanity subdomains to help users present a more polished product. Custom Domains allow users to use their own domain for their Supabase project, while Vanity Subdomains enable them to choose a relevant subdomain on Supabase's domain. These features are now generally available as paid add-ons through the Supabase dashboard and closed beta, respectively. However, there are some limitations such as Edge Functions not supporting custom domains or vanity subdomains yet, and only one custom domain or vanity subdomain per project being allowed currently.