It would be great to have an option to block a site (via the domain list and not a simple search boolean) from the search results. Ideally there would be an option under each returned site's context menu for "add to list".
Currently, my workflow is to gather up all of the AI slop/garbage sites returned from a search into a text file, then import that en masse into my block list.
Since Kagi is the only search engine that even allows a user-defined block list (and is the primary reason that I happily pay for the service!), it's difficult to say how others have implemented it.
The closest existing feature is the "block site" option which simply appends "-site:xyz.com" to the search. My suggestion is this, only permanent.