So what does that process look like? Is there a formal process with clear method on how and when the decision is made, how it get propagate into a decision and how the documentation and announcement to users will be?

Is there a formal policy document you can link me that defines the process how additional data collection are added in mozilla projects? It seems to me that what we have is a in-prompt discussion because people happen to detect a change and managed to raised the issue just before it went live. A formal process would make people trust the project that issues like this isn't depended on the chance that a data collection will be detected before it goes live and only then be brought to discussion in the public mailing list.