Until I left FS in 1988, in an AFIZ all traffic got full info on all other traffic. Outside AFIZ, IFR always received full traffic info on IFR and known VFR, except when really busy, you could pass the VFR traffic as multiple VFR traffic in your area. Only ever used it during Birdsville Races weekend. One I remember was an FK27 taxying Moomba for Adelaide, pilot responded with give me a hint, I said don't go East, as most were tracking via Innamincka or thereabouts.
Doubt those rules changed before the demise of FS.