If I understand Salt Typhoon correctly it's a masterpiece. The descriptions I've seen indicate that they penetrated lawful intercept. Lawful intercept operates outside network operators network management systems because it was designed not to trust the network operators. I am skeptical of claims that Salt Typhoon has been eliminated from US networks. Any such implicitly claim to detect lawful intercept traffic and ensure it isn't nefarious, which traffic that system is designed to hide.