The tweet mentions a bypass for Cloudflare WAF using an XSS payload. The payload used is <img src=x onerror=alert(1)>. This bypass can be used to execute a JavaScript alert on the vulnerable website. This bypass can be significant for security researchers and website owners using Cloudflare WAF. For more technical details, check the tweet link provided.
Check out the original tweet here: https://twitter.com/bl4_ck7/status/1818070787917484366