The first argument of Deterministic is the name you give the variable. In your case, you are naming it “μ[1]-μ[0]” which is why ArviZ uses that name. The easiest way to fix this would be to use the name you want here directly.
The first argument of Deterministic is the name you give the variable. In your case, you are naming it “μ[1]-μ[0]” which is why ArviZ uses that name. The easiest way to fix this would be to use the name you want here directly.