You may or may not trust these sources, however, even just the fact that at one point Durov was extremely afraid of being found by FSB, Telegram being the only network not blocked in Russia, and general embrace of Telegram by Russian propagandists, speaks for itself.
https://www.wired.com/story/the-kremlin-has-entered-the-chat...
https://euromaidanpress.com/2023/04/07/russian-fsb-has-the-k...
https://pdmnews-ru.translate.goog/25704/?_x_tr_sl=auto&_x_tr...
You may or may not trust these sources, however, even just the fact that at one point Durov was extremely afraid of being found by FSB, Telegram being the only network not blocked in Russia, and general embrace of Telegram by Russian propagandists, speaks for itself.