TL;DR: With Firefox 56, Mozilla combined Firefox Health Report and Telemetry data into a single setting called “technical and interaction data”, which was then enabled by default. This data was then shared with advertising partners on a de-identified or aggregated basis.
I agree - so the question is if anything changed – Mozilla has said that they are just clarifying their existing usage of data. Hence my read. Yes, this implies that Mozilla was previously deceptive and is being more transparent today, but that is also what they are saying.
If you disagree, I’d be curious to see where we see that Mozilla has explained that the new Privacy Notice is describing new practices by Mozilla rather than a clarification of their existing practice – basically, why do you believe that.