OK, this was a mistake from me. I tried to cover all bases, but I missed one. We have had these RSSLink methods spread around on both site and page (the latter is deprecated and should show a proper warning).
The recommended way to link to your RSS feed(s) is described here:
If you want to link to your “site’s RSS feed”, use the home page as starting point:
{{ with site.Home.OutputFormats.Get "rss" -}}
{{ printf `<link rel="%s" type="%s" href="%s" title="%s" />` .Rel .MediaType.Type .Permalink site.Home.Title | safeHTML }}
{{ end -}}