Following Russian's ban, Telegram will soon be losing more customers. In this case, the French government is testing an encrypted messaging app that would keep officials' data on servers located within the country. The government is worried about “potential breaches” that could take place if data was encrypted in the US or Russia, and who can blame from, honestly.
Facebook's data issues with the whole Cambridge Analytica situation, and Russia's demand for Telegram's encryption keys, the country has every right to be concerned about their data and sensitive chats that could potentially end up in the wrong hands. Right now, only 20 officials are testing the app, but ideally it may become mandatory for the government by the summer.
What could have prompted the change may be due to France's leadership. President Macron, his inner circle and other officials have been using Telegram to chat about work. It got to the point where Macron reportedly appears online into the early hours of the morning. While Telegram does offer strong encryption and the fact that officials tend to not discuss secrets or strategic information on the app (according to spokesperson that talked to Bloomberg), this still leaves high-level talks on a third-party service that isn't vetted by France.
How helpful this will be for France's government remains to be seen. The developers behind the app will need to be certain that hackers can't compromise the encryption keys and intercept messages. If this does work as promised, this could set a new precedent for countries to have their own secure chat apps for government use.