The tweet highlights a security lesson regarding Web Application Firewalls (WAFs). It advises that stripping or removing parts of user input before it reaches the WAF may not be effective for security. When a WAF is positioned between the user and web application, manipulating input by removing characters or patterns beforehand can lead to bypassing the WAF protections, especially for XSS (Cross-Site Scripting) attacks. The message serves as a general caution for developers and security professionals implementing input filtering alongside a WAF: it is better to rely on the WAF's full inspection capabilities rather than prematurely altering input which could create security gaps.
For more details, check out the original tweet here: https://twitter.com/KN0X55/status/2033923996903715309