Does anyone know what PCSCK mirroring status is?

We have been down this road before. The undocumented name was created by an Apple Engineer having to do with iCloud and only has meaning to them. I even posted the log on my iPhone showing the same exact thing We all have it and does not mean your device is compromised.

Only Apple engineers would know for certain what that is and why they chose that name. But it's nothing nefarious. Not everything with the word "mirror" in it means something bad.