The tweet demonstrates a bypass for WAF filtering parentheses in the context of XSS. It utilizes a payload '? onerror=alert;throw 1 ?' that avoids using parentheses by setting alert as the global error handler and then throwing an error using 'throw 1'. This bypass technique can evade WAF filtering mechanisms. More technical details can be found at the provided link.
For more details, check out the original tweet here: https://twitter.com/WebSecAcademy/status/1923751381682233632