While this article claims, "Durov offered no proof for his theory ...", this article - https://thewire.in/tech/telegram-ceo-alleges-reliance-used-b... - points out that Durov did share screenshots from a "BGP toolkit" to substantiate his point. (Also, Durov has claimed that they are sabotaging access to Telegram users outside India; Telegram is already temporarily banned in India for a week ...).

Here's the X Thread - https://xcancel.com/durov/status/2066945969854234977

Related article with details of the BGP hijacking: https://news.ycombinator.com/item?id=48601514