Telegram stores all data on own servers.

Just try the following trick:

- in a private Browser window open web.telegram.org

- enter your phone number, receive the code

- turn on flight mode on your phone

- now enter the identification code in your browser

- access your whole chat history while your smartphone can definitely not act as a source

Even WhatsApp is better in this regard.

Article in German: https://www.heise.de/hintergrund/Telegram-Chat-der-sichere-D...