Perplexity claims that you can “use the following robots.txt tags to manage how their sites and content interact with Perplexity.” https://docs.perplexity.ai/guides/bots

Their fetcher (not crawler) has user agent Perplexity-User. Since the fetching is user-requested, it ignores robots.txt . In the article, it discusses how blocking the “Perplexity-User” user agent doesn’t actually work, and how perplexity uses an anonymous user agent to avoid being blocked.