Considering Russia’s huge reaction to the arrest of Pavel Durov and the quick statement that they will develop their own alternative to Telegram, one can probably assume that Telegram is part of the Russians’ information gathering.
The entire Ukraine war plan could exist somewhere in Telegram's data storage farm.
Clearly, ruzzia is worried that Pavel Durov will give France the back door password to all of this data.
IMHO, this is the only rationale for putin's order to delete all Telegram data/files.