Favicon missing when subscribing from RSS-readers.

[dantemogrim]

Here's a link to my nuxt-config.js in the repository I'm having trouble with.
The feed itself works as it should but whenever I or someone else wants to subscribe from any RSS reader, the favicon never shoes up and gets replaced by a dummy icon instead.

Here are some links for troubleshooting:

• The repository.
• The XML feed url.

Is it a bug in the module or have I configured something wrong?
I've tried changing things around in so many ways, I'm running out of ideas at this point.