StructuredBuffer is reflected as constant buffer

Description
StructuredBuffer varName: register(t1) is being reflected as a constant buffer

Steps to Reproduce
https://shader-playground.timjones.io/dceaeee1d51b72b3e87ac7e6146c77bf
i'm trying to implement average luminance hdr and the shader above is reflecting t1 as a constant buffer while doing this
D3D12_SHADER_DESC shaderDesc{};
shaderReflection->GetDesc(&shaderDesc);

Actual Behavior
doing this will enumerate AverageLuminance as a constant buffer
for (unsigned int paramIdx = 0; paramIdx < desc.ConstantBuffers; paramIdx++)
{
auto cbReflection = reflection->GetConstantBufferByIndex(paramIdx);
D3D12_SHADER_BUFFER_DESC paramDesc{};
cbReflection->GetDesc(&paramDesc);

std::string cbufferName(paramDesc.Name);

Environment
dxc.exe --version
dxcompiler.dll: 1.8 - 1.8.2407.7 (416fab6b5); dxil.dll: 1.8(101.8.2407.12)
Win11

if this behavior is expected please discard the bug

The report names no repository files or tests; start with the linked shader-playground reproduction and the D3D12 reflection entry points shown, including GetDesc and GetConstantBufferByIndex. Determine whether StructuredBuffer at register(t1) should appear among constant buffers; done means establishing the expected behavior and locating the relevant compiler or reflection test area.