I have no evidence beyond a detective-like suspicion, but I would not be surprised to learn that the meltdown of Optus last week was in the end linked to a cyber-attack, which would include internal sabotage. Mere problems arising from software and other blah blahs, does not to my mind explain the extent of the problem, but, I am not an expert, at anything at all, really. However, Optus did have a cyber-attack in 2022, and it has just legally failed to keep secret a report on that. It would be interesting to see, if the report gets in the public domain, any clues that may be in it. The system is nervous about admitting to cyber-attacks as it scares people, as these attacks show that the IT system has feet of clay and is extremely vulnerable if the right nasties target it.
For example, the entire population of the US state of Maine has had their data stolen by on-line thieves. This arose as a ransomware attack that the authorities discovered on May 31 this year. It has impacted upon 1.3 million individuals. And, if it can happen there, it can happen here too.