So to make it clear, it's because their company actually holds some data for clients that these governments want access to - because telegram is not peer-to-peer, unless you set a chat to private.
In essence Telegram as a company holds a lot of data that the French authorities want access to...
This comment brought to you by the Signal gang.

It's not a fight, it's logic. The world governments can do nothing to OpenWhisperSystems (the makers of Signal), because they don't store any communication.
Telegram however thought they were smart, by storing data and splitting that data up in to several different pieces around the world, assuming governments wouldn't collude together to get it.
But they didn't foresee the litigious nature of nation states, and that's what we're seeing now. If these nation states also start to collude with one another, everyone who thought they were safe are gonna get fucked.
Signal does not store any communication data. They only facilitate handshake between clients and the clients manage the data between themselves.
This is why Telegram isn't safe, but Signal is.