According to Google, Play Services 26.31 adds a Health and Fitness change for Wear OS that processes raw location measurements server-side to produce a more accurate workout route. Galaxy Watches run Wear OS and Play Services, so they are covered. The GPS hardware on the wrist is unchanged. The cleanup happens on Google's servers, which is why the improvement arrives in a Play Services update rather than a watch firmware release.
A Galaxy Watch with cellular receives the corrected route directly on the device. Every other model gets it only after reconnecting to Wi-Fi or a paired phone, so the run is over before the map improves. Samsung usually tests Play system updates before rolling them out to Galaxy devices, so the date is not Google's to set. Google has not explained what the feature does when the watch stays offline for a whole workout, which is the ordinary case for a non-cellular watch when the phone stays at home.