Interesting. At our org we always do both. Root cause, what are we changing. I assumed that was standard practice.

If you just explain what happened and why, that's fine but...how are you going to make sure it doesn't happen again?

The problem I found more vexing as a manager was: how can you prevent this KIND of problem from occurring?

I'd have someone on my team make a technical error and xyz wouldn't work. Wed talk thru it, and they wouldn't make that exact mistake again. But there's literally 10k things that can go wrong in our system, so then a related mistake would happen later.

What they needed was improved pattern recognition vs if this / then that which comes from post mortems.