If you turn off tracers you only turn them off on your end, everyone else will see tracers coming from GVs, field guns, and aircraft gunner postions.
yeah this is dumb - if I have tracers off for fighters (I dont but I have done) they also dissapear for me when in field gun or osti, even though everyone else can see them. they need to be set per aircraft/vehicle/etc, or by class fighter/attack/bomber/vehicle/gun (ideally) rather than globally. might wishlist this...