Interestingly, I've never seen Telegram content being served from a network outside their own registered ASNs (AS44907/AS62014) – Can you share some examples of CDNs they use?
Also to note, on all the popular network providers (Jio, Airtel etc), I've always observed Telegram download/upload speeds to be inconsistent, ranging from 1Mbps to 1Gbps fluctuations
regardless of the upstream provider and/or latency towards the IP the content is being served from.
--Best Regards
Daryll Swer