Wasn't Pavel Durov the billionaire CEO under investigation and put into jail in France to be coerced/forced to build a backdoor into Telegram for the French Gov

Wasn't Pavel Durov the billionaire CEO under investigation and put into jail in France to be coerced/forced to build a backdoor into Telegram for the French Government? He just recently came free. I don't know if there is any proof that Telegram is not backdoored by now. Even if someone can analyse all binary releases and reverse engineer the code. It's more likely Telegram servers are backdoored and not the clients.