Well, since your original y array used to have values of at least 0.00465423, whereas the plot is limited to |values| < 4e-11, I must have made a small mistake with my code cleanup suggestion.
For one, I’ve noticed I made a copy error here:
y = run!(model, sin.(2π*f .* t))
I should have used fsig instead:
y = run!(model, sin.(2π*fsig .* t))