I wonder what "encrypted messaging app" she was using and how did the authorities know what was being sent. Article linked, please speculate below

https://www.military.com/daily-news/2022/02/18/marine-reservist-nurse-charged-fake-vaccine-card-scam.html.
*"Covering their tracks by referring to “gift cards,” “Cardi Bs,” “Christmas cards” and “Pokemon cards,” Liu and Rodriguez conducted the scam through encrypted messaging apps and social media and instructed buyers to mask online payments as “consultancy” or “Korean BBQ,” the indictment said."*

app article encrypted messaging messaging app privacy