I don't know if this is a bug or if this wasn't added or if it was added but in the patch 8 hotfix it says that gnomes can now be destroyed and in which they have a new sound effect. However, I tried pushing it around and throwing stuff at it, it doesn't break. Here is the proof of the hotfix patch thing that was mentioned about the gnomes.
#No New Sound Effect Coming From The Gnomes
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There was no mention of destroying the gnomes, they mean breaking them.
There's no sound effect