Isochrone foot-walking smoothing seems broken

Hi folks,

In the isochrone API for the foot-walking profile, the smoothing parameter seems to have no effect.
See for example the two GeoJSON responses for smoothing 0 and smoothing 100 about the same point:

They are identical.
Is this a bug?

I have tried this on several other points with the same result.

for small isochrones (<5000m), the smoothing factor is limited. Isochrones can be so small that changing the smoothing factor has no effect, as the smoothing is already at its limit.
If you request larger isochrones, you should see effects of the smoothing factor.