It doesn't actually even matter if they did this. The only thing that matters is that they are physically capable of doing so. Telegram is not e2e encrypted by default, and therefore you shouldn't use it if you're concerned about privacy.
Look no further than Signal's supboenas and how they respond to them. With all the information they hold about an account. Which is just the creation date and last connection date. https://signal.org/bigbrother/eastern-virginia-grand-jury/
Look no further than Signal's supboenas and how they respond to them. With all the information they hold about an account. Which is just the creation date and last connection date. https://signal.org/bigbrother/eastern-virginia-grand-jury/