Problem with Plugin "Simply Exclude"

On my Blog https://www.angis-blog.de/ I wanted to exclude a category from the main page with the Plugin “Simply Exclude”. But somehow that doesn’t work.

There is a part in the plugin settings that says “The Simply-Exclude plugin was designed to only work with the main page query. But sometimes other plugins or your theme will effect how the main filtering works. So if you are having trouble attempting to filter categories from your home page you might want to try and set this option to ‘All’ and see if it corrects your issue.” So I thought this might be the problem. But even if I set this option to All, I still see the category “Schleich Pferde”. Instead it excludes the posts from recent comments and recent posts in the sidebar.

I also choose exclude in the feed and for me it does exclude the posts from this category in the feed, but some other people told me that for them the posts are still there.

I’m really confused! Help, anyone?