It isn’t a sign of anything as evidenced by the fact that these groups used Telegram in the pretense that it was “anonymous”.
Now, they’re flocking to SimpleX, which may be better, but isn’t without censorship.
Poberezkin … believes that despite his network’s focus on privacy, SimpleX can curb the spread of terrorist or abusive material on its app.
“Even in these early days we already did more to prevent distribution of [child sexual abuse material] via the preset servers included in the app than many other platforms did, even though they have much more control. While we cannot indiscriminately scan all content … if the group entry point is publicly promoted and can be joined, and it uses the servers that we operate, we can remove these entry points and the files from the servers.”
At which point, one might also use Matrix clients, or any of the other alternatives.