Offering a browser extension (which does not require using Kagi or being subscribed) that modifies other search engine websites + lets people report slop from anywhere would not only benefit Kagi users but also make the internet a better place for everyone using the extension. A business benefit would be that since this is a product associated with Kagi, it would funnel people into using Kagi itself.
A major concern is abuse, but there probably is a nice way to handle it.
Right click on anything -> report website as slop. Or press the extension in the menu and report as slop from there. Or in a supported search engine, inject HTML to report slop.
Show a slop indicator in the extension if the current website is slop, or an indicator on hyperlinks that link to slop. Would work anywhere on the web.