I use GRAV as a blog. No problem with the feed plugin and syndication buttons on the page with the list of articles. But the url of these buttons are bad for all other pages: page with a complete article, contact page, author’s page,… I think the problem is the variable {{ feed_url }}. I don’t find where this vaiable is created or assigned in the feed plugin.
Could you help to find this variable?
At this time, I modified the file “sidebar.html.twig” in the template, like this :
Have you updated to the very latest version of the plugins? and if you based your theme on Antimatter, had a look at latest version of that also?
A month or so back, I addressed this very problem. Basically I calculate a different base_url local variable in blog.html.twig and item.html.twig so that the links for these plugins is correct on each page.
BTW, your solution will work too. However, your just setting feed_url to blog every time, so not sure the need for the if()
If you need to access from various pages you could set a site wide global variable in you site.yaml file and reference that. My changes were an attempt to make the theme not require a configure option like that, but if it works better for your use case there is nothing wrong with it.