It's possible he's engaged in criminal behavior, but based on the info below my guess is he's being charged with crimes others are committing through telegram due to his unwillingness to police the platform.

He also directly ignored the US' attempt to stop him from creating a shitcoin (which is currently a top ten). It'll be an interesting story to watch.

The end result is protocols over platforms 🙂

Info:

BFMTV reports that the Telegram founder was put on a wanted list just minutes before landing in Paris, and an arrest warrant was issued.

Durov "will be presented to an investigating judge this Saturday evening before a possible indictment on Sunday for a multitude of offenses: terrorism, narcotics, fraud, money laundering, receiving stolen goods, pedo criminal content," TF1 reports.