Ignoring reflection of specific objects for MeshTransmissionMaterial

[LordUwe]

It is said that "If you have other objects that you don't want to see reflected in the material just add them to the parent mesh as children."

I added the object I don't want to see/reflect to the one with the MeshTransmissionMaterial as child element. But unfortunately it is still reflected in the material. Can anyone help me here?
Thanks!

https://codesandbox.io/s/tender-sun-ct5wot?file=/src/App.js