Sometimes, when visiting articles using the RSS feed (http://gamingonlinux.com/article_rss.php?mini I'm not logged into my account. I usually open a bunch of articles at once and I'm logged in for most of them but for some I am not. It doesn't always happen and I can't reproduce it by clicking on the link again (I'm usually logged in when I do that so it doesn't seem to be caused by any specific kind of articles). Refreshing the website automatically logs me in (like I am supposed to be).
Happened today with https://www.gamingonlinux.com/articles/a-linux-beta-build-of-solstice-chronicles-mia-may-come-soon.11803 . Like I said, I can't reproduce it by following the RSS link again.
It's not much of a problem but I thought I should report it anyway.
It could also be a problem on my side since I'm using several browser add-ons including one to manage RSS subscriptions (don't think it is since the links aren't modified by it).
Firefox's Javascript debugger only gives a single error and I doubt that that is related: Source map error: request failed with status 404 Resource URL: https://www.gamingonlinux.com/includes/jscripts/autocomplete/easy-autocomplete.min.css Source Map URL: easy-autocomplete.min.css.map

Further infos:

Spoiler, click me

User agent string: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Add-ons: Brief (an RSS manager), uBlock Origin (doesn't block anything on GamingOnLinux), uMatrix (only allows 1st party scripts (there usually aren't 3rd party ones anyway), forbids mixed content (http/https) and web workers, spoofs Referer header and spoofs noscript tags)

Edit: Forgot to mention that it only started to happen somewhat recently, maybe a week ago.