I just checked, now it shows the correct title.
My assumption is the thread creator first created the thread with the "toilet" word, then corrected it and it somehow didn't update in the sidebar. After replies were posted, the thread title updated in the sidebar accordingly.
I have no translation plugins, never had. The issue was shown both in Edge (which I am not using daily, vanilla install) and in Chrome (which I use all the time).
So maybe test by creating a test thread, editing its title and see if the change reflects in the sidebar.