Can you elaborate on this?
https://www.npr.org/sections/coronavirus-live-updates/2021/1...
People running what amounts to blogs on Telegram, and reaching a wide audience. Nominally they're groups but only one person can post. They can run ordinary blogs on the web and not get many readers, they can post on Facebook but the moderation there is said to be effective now. Telegram provides them with a large audience and no moderation. https://en.wikipedia.org/wiki/Attila_Hildmann
Nazis looking for groups where they can recruit. The cliché is a group set up to organise protest against e.g. some new gravel pit in what was a quiet little forest, where a couple of nazis join and then mention that this gravel pit is really just another example of how capitalist jew pigs grow rich at the expense of ordinary people like the neighbours of that gravel pit. It's not clear to me why Telegram works better for them than Facebook groups. Perhaps a question of moderation style.
A Signal group is private to the members, always and by design. You can only join by knowing someone in the group, and only read the messages by being in the group. Telegram has groups that you can find by searching, and that you can join and read without knowing anyone else in the group. That kind of group is central to several of the big problems in German society at the moment.