The announcement of the leak (by Zakharov[1]) was in https://t.me/zakharovchannel/1418.
Alburov[2], former head investigative journalist at Navalny’s ACF[3], confirmed(/bragged) that the the data matched their publications in https://x.com/alburov/status/1828143239615947234.
The source for most of the news articles on Durov specifically, published in iStories[4], is https://istories.media/news/2024/08/27/pavel-durov-priezzhal....
[1] https://en.wikipedia.org/wiki/Andrey_Zakharov_(journalist)
[2] https://en.wikipedia.org/wiki/Georgy_Alburov
[3] https://en.wikipedia.org/wiki/Anti-Corruption_Foundation
[4] https://en.wikipedia.org/wiki/IStories