If you're looking for something like Web3 Antivirus, there aren't many close alternatives. But Beagle Security has a suite of penetration testing tools that uses AI to identify and patch vulnerabilities in web apps, APIs and GraphQL interfaces. It's not specifically geared for Web3, but its serious security tools could help you protect your Web3 wallet or other apps that interact with it.
Another possibility is AI or Not, an AI detector that can spot AI-generated content, including images, audio and identity documents. That can help thwart fraud and scams by detecting deepfakes and generative AI. It's not directly related to stopping Web3 shenanigans, but its ability to identify and block AI-generated fraudulent content could help keep the Web3 world safe.