I.e. this article from October: https://www.techradar.com/pro/chinese-hackers-allegedly-hit-us-wiretap-systems-to-hit-broadband-networks

In an all too predictable turn of events, Salt Typhoon, an infamous Chinese state actor, has reportedly hijacked government systems to breach several American broadband providers and gain access to the interception portals required by US law.

They did. That's the reason for this hack, they wanted Lawful Interception, they got their backdoor. It's what professionals and privacy advocates said all along, if it exists it will be abused.