Telegram vs Signal is really a moot comparison in the technical sense.
It is more of a question, who would you rather read your messages ? USA or Russia ?
Because even if there is E2E encryption and an open source client, unless you review it and compile it yourself, there is nothing to say that your messages are relayed to some agency's datacenter after decryption. The USA has all the legal framework necessary to achieve that with the tremendous power of the "intelligence" agencies, and Russia.. well.. doesn't even need that.
Telegram's founders are in exile from Russia after the Russian government took over their previous venture (Vkontakte). It is misinformation to associate Telegram with the Russian government.
Nikolai Durov lives in Saint Petersburg and works for the Russian Academy of Sciences. Pavel Durov had visited Russia multiple time since his "exile".
The public-facing story around Telegram is performative PR, which could be explained by the exact reasons listed in the parent comments: association with the Russian state had hindered VK growth besides the CIS region.
It is more of a question, who would you rather read your messages ? USA or Russia ?
Because even if there is E2E encryption and an open source client, unless you review it and compile it yourself, there is nothing to say that your messages are relayed to some agency's datacenter after decryption. The USA has all the legal framework necessary to achieve that with the tremendous power of the "intelligence" agencies, and Russia.. well.. doesn't even need that.