Terrain vertex displacement In Unity 6

[maidnmate]

So apparently Vertex displacement is not allowed in Unity 6 terrain? Am i doing something wrong?

Screenshots below are with and without displacement accordingly

P.S. displacement of positionWS doesn’t do anything and i don’t really understand why so I would greatly appreciate any help

Varyings SplatmapVert(Attributes v)
{
    Varyings o = (Varyings)0;

    UNITY_SETUP_INSTANCE_ID(v);
    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
    TerrainInstancing(v.positionOS, v.normalOS, v.texcoord);

    v.positionOS.y+=4;

    VertexPositionInputs Attributes = GetVertexPositionInputs(v.positionOS.xyz);

    o.uvMainAndLM.xy = v.texcoord;
    o.uvMainAndLM.zw = v.texcoord * unity_LightmapST.xy + unity_LightmapST.zw;
 
...
}