[rurban]

As trusted execution env has nothing to do with sniffing network traffic or have access to main memory, IO, CPU registers .

So why does it do so? Because it's merely a backdoor, not a trusted enclave.

[gray_charger]

A TEE has nothing to do with any of that. A TEE is a CPU feature that generates a physically separate area of memory that no other process can access to protect sensitive data from even the OS (in case of compromise).