That’s strange, I had heard that multiple times.
Also the tracers are colored to indicate sweet spots, and even have descriptors of those sweet spots in the options.
Edit: Double-checked. Yeah, in the settings where you can enable tracers, it pretty explicitly states green tracers as “additional damage tracers” which is obviously not currently in the game.
Additional damage tracers are simply extra tracers that some protruding weapons have on top of the straight tracer, like the axe. They exist to improve the collision accuracy by making the head connect before the shaft in some cases, but were never used or intended as sweet spot tracers.