* Gov't is mandated to use AWS Gov instances which are quite easy to distinguish [2].
* there are ways to bypass those rootchecks to make a rooted phone seem not rooted [3].
[1] https://en.wikipedia.org/wiki/Deep_packet_inspection#United_...
[2] https://aws.amazon.com/blogs/security/aws-govcloud-earns-dod...
[3] https://stackoverflow.com/questions/68661134/root-detection-...
That's not, in fact, true. The certifications that apply to AWS Gov make it easier to meet certain government compliance rules that apply to certain categories of data, but it is possible to meet the standards on a platform that isn't certified or certified to a lower level (but it means more administrative work for the org using the platform) and many Commercial AWS offerings have FedRAMP certifications, anyhow. I work in an org touched by FedRAMP, and which is almost entirely on AWS commercial, not Gov.
Consider that they wouldn't have to tell us, indeed, might face criminal penalties for disclosing it.
Conclusion: the FBI can do this.
* if packets are only sent via carrier, not wifi
* if packets are sent to aws instances, which is very common
* if it all stops when phone is rooted, which is common for many apps