Highlight or hide works you kudosed/marked as seen.
< Feedback on AO3: Kudosed and seen history
Sorry the new version isn't working for you. If you want to revert to the previous version, you can find it here: https://greasyfork.org/en/scripts/5835-ao3-kudosed-and-seen-history?version=231614
Random works appearing in your history are most likely not caused by this userscript. The only way for it to affect your history is if you manually use the "Check for bookmarks" button in the menu, and then it works one time for works on the page you're on at the time. Just browsing won't cause it.
After upgrading to the latest Version 2.0, the script doesn't really work anymore and the works I've previously marked as seen already keeps reverting back. I also noticed random works that I don't read (e.g., not from my fandoms, in a different language, or even having warnings such as non-con that I avoid vehemently) appearing in my history despite never clicking on them!