Yes, surprisingly, there is no other news source that I've found as yet.
Worth noting, in the email from HIBP, they include the following full information: "Breach: Trello
Date of breach: 16 Jan 2024
Number of accounts: 15,111,945
Compromised data: Email addresses, Names, Usernames
Description: In January 2024, data was scraped from Trello and posted for sale on a popular hacking forum. Containing over 15M email addresses, names and usernames, the data was obtained by enumerating a publicly accessible resource using email addresses from previous breach corpuses. Trello advised that no unauthorised access had occurred."