Why do you consider telegram private? It's a pretty bad option for that.
They are only using true end-to-end encryption when using the explicit "secret chat" feature, which is limited to one-on-one still, afaik.
"Normal"/default encryption gets resolved on telegram servers, so your clear text messages are sitting there for them to do whatever they want. Given that telegram is based in UAE and has knownRussian management influence,I'd be extra hesitant.
It also is for-profit and closed-source for the servers ( only clients are open source), so nobody knows what the servers really do.
If you care about privacy, go use Signal or any Matrix-based messenger such as Element. Especially because they lack zero of the comfort and usability that Telegram offer, but are much more secure.