Recently, after my computer get repaired, I had to do various things, such as reinstall some software and, in the case of Firefox, put back my bookmarks and rss feeds (they were lost and if there was a backup, I didn't find it) The problem only happen with [https://suihira.com/comic/rss this page]. I didn't find any other page with this problem. I checked all what I can about this page (using view-source). I compared it with other xml files, mostly other rss, and the documentation I found about rss, xml and html. Visibly, this is a regular xml/rss page. I didn't found anything special in. There are element underlined in red in the source code but it is mostly what can be seen as an error if this is parsed at assuming it's html code. I also check what I get if I do a right click then, in the contextual menu, I select "inspecter" (sorry, on my computer, Firefox is set to french and I don't know the english term ; this is the last entry of the menu). I got a different code. Apparently, Firefox applied (pseudo) fixes to display the page as an html document. I checked the name of the page. This is unusual but, in my rss feeds, there are several other rss feeds named this kind of way and all of them work properly. The last thing I checked is the RSS link that is on most pages of the site and send to this glitched page. It doesn't seem to be more the cause. Visibly, for an unknown reason, Firefox decreed this is html code and I found no way to make it reconsider this or parse this page as xml. It seem the first mention of problem with the rss feed on this site was [https://suihira.com/comic/355 a comment] written almost four months ago but I don't know if it was the same problem.