I see what you mean nostr:npub18ams6ewn5aj2n3wt2qawzglx9mr4nzksxhvrdc4gzrecw7n5tvjqctp424 , when I searched your image, there were many nostr.build linked results. Although I did see results for primal and nostrcheck.me also.
I am thinking they search all links on the public internet, curious if nostr:npub137c5pd8gmhhe0njtsgwjgunc5xjr2vmzvglkgqs5sjeh972gqqxqjak37w knows if we can specifically block them..