The tweet mentions the discovery of a unique Stored XSS vulnerability by bypassing a Web Application Firewall using a Characters Limitation Bypass technique. The author found their first vulnerability in the context of Bitcoin technology and trading. The details of the bypass and vulnerability are not provided in the tweet, so further analysis would be needed to understand the technical aspects of the bypass.
For more details, check out the original tweet here: https://twitter.com/neni_db/status/1833542118553338031