Well.... it might (unlikely, but...) have implications for the Russian military forces in Ukraine, who are widely using it for communications (even for things like targeting artillery with drone spotters).
Interestingly (and understandably I guess, given the original nationality of the current CEO), the Ukrainian military are mostly using Signal, and the Russian military almost exclusively use Telegram.
Last I checked, Durov had some of his biggest companies confiscated by the Russian government, and he basically fled Russia, so it's hard to believe he would be cooperating with them. (But not impossible I guess, they might have scared him into cooperating ??)
Also, doesn't the Ukrainian military also use Telegram quite a lot ? (And what about the Israelo-Japanese Viber, also very popular in Ukraine?)
it is hosted on Dutch and Western servers, and most chats are not e2e encrypted, especially group ones where you coordinate things like that. They are just incompetent and sloppy to use it for military, which probably already suffered for it greatly, but all the data was flowing unecrypted to closed-source servers in the Western Europe this whole time, so this has no new implications for anything.
Interestingly (and understandably I guess, given the original nationality of the current CEO), the Ukrainian military are mostly using Signal, and the Russian military almost exclusively use Telegram.