Unity: How to edit vertex after skinned mesh animation has been applied

Question

As a test im trying to move an animated skinned mesh up and down per vertex but it doesnt really work.

without offset

with offset 1 in the y

Im fairly certain that the vertices im changing are before the animation is applied. How would I go about changin the vertices after it has been applied

heres my compute shader code

// Each #kernel tells which function to compile; you can have many kernels
#pragma kernel TriangleParticle

RWByteAddressBuffer bufVertices;
RWByteAddressBuffer bufIndices;
StructuredBuffer<float3> bufOldVertices;

float triDist;
float trilerp;
float time;
float3 target;

[numthreads(64,1,1)]
void TriangleParticle (uint3 id : SV_DispatchThreadID)
{
    float3 vertPos = bufOldVertices[id.x];
    vertPos += float3(0, trilerp, 0);
    bufVertices.Store3(id.x * 40, asuint(vertPos));
}