This tweet talks about a WAF bypass related to Server-Side Template Injection (SSTI). It indicates that if a WAF is blocking basic SSTI payloads such as {{ config }}, it means simple attack attempts are already filtered. However, the tweet suggests that more advanced bypass techniques exist to circumvent common SSTI filters that use simple blacklists. These filters often block straightforward payloads, but attackers can employ more sophisticated methods to bypass the filters and execute SSTI attacks. The tweet promotes a thread explaining these advanced bypass techniques, which would be useful for bug bounty hunters and security researchers to understand and test their defenses against SSTI vulnerabilities beyond basic payloads.