[jmkb]

GeoApify[0] is one of these commercial services using OpenStreetMap data. They have a no-friction isochrone "playground"[1] that's sufficient for casual exploration. You can switch the travel mode to "transit" to include train routes, but the maximum travel time for the demo is capped at one hour.

The results are very different, eg chronotrains-eu.vercel.app claims that Wittenberge is within an hour of Berlin Hauptbahnhof, but GeoApify won't take you further than Nauen. Possibly chronotrains-eu is showing a best-case travel time while GeoApify is attempting to calculate realtime travel using the current day's schedules?

I doubt the main OSM site would ever host an isochrone demo, as it's more of a reference implementation of very basic map and routing features that OSM data enables. Notably, the routing demos there do not (yet) include any kind of transit mode.

[0] https://www.geoapify.com

[1] https://apidocs.geoapify.com/playground/isoline

[Dagonfly]

Seems like OPs site is correct. There are multiple connections with 54min and occasional ones with 47min.

Though on geoapify you select a a street address rather than the train stop. So maybe they add a few minutes buffer for walking to the station.