There is an still ongoing huge political and criminal scandal: a shady mafia-like figure (Marian Kocner) has (allegedly) ordered the murder of a journalist. The journalist and his girlfriend were shot and during the investigations Kocners phone(s) were found (or more exactly another shady person gave them to the police). Not only were undeleted Threema messages extracted, but also (allegedly) many deleted Threema communications were succesfully extracted and presented in court.
While Kocner was in that particular case exonerated in first instance (it's now in the Highest Court), the messages were leaked to the press and led to the abdication of the then prime minister (Robert Fico), the loss of the then ruling coalition in the next elections, and now because of those decoded messages, many judges, prosecutors, politicians, policemen etc are locked up and investigated - Marian Kocner directly gave them orders through Threema. The former head of police has even hanged himself in the prison a few days ago (because of a different, but connected, scandal). While this is more about the general state of affairs in Slovakia, it's interesting how the compromised security of an app they thought was "fully" secure has impacted the Slovakian political landscape.