While very long, it doesn't look like that article provides anything but speculation. What would you say is the key point? Where's the meat?
I know that it would be hard to get good evidence here but I still think the burden of proof lies on the more extreme claim. Which to me is that a company founded by someone fleeing oppression would work directly with the oppressor.
The example of messages appearing as 'read' does not imply to me that telegram is working with them - rather that the her app was compromised by other means. Otherwise, why create such a flaw in your monitoring?
Meduza - news organization criminally charged in russia operating in latvia - is mostly accessed in russia via telegram. It's hard but not impossible to imagine that the russian government would allow it to remain uncensored.