The timing of this aligning with Pavel Durov's arrest makes it seem like propaganda. There doesn't seem to be anything new, most of it happened prior to 2024.
The first discussion I have found of it is Hope Not Hate's "State of Hate 2020" report. It hasn't been mentioned in the more recent reports. [1]
[0] - https://www.gov.uk/government/news/terrorgram-collective-now...
[1] - https://hopenothate.org.uk/wp-content/uploads/2020/03/state-...