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.
So does Icecat and it even cuts out sync as well, where LibreWolf leaves it in and disables it by default, leaving it up to the user to enable at their leisure.