I cannot check other routes atm but at least for the “Greatest London Flat” the distance and elevation are wrong in the companion app (latest android version)
Looks like it has a substantial lead-in
But I have reported other data issues with the Routes menu, like incorrect gradients on KOMs. It says Zwift KOM is 0.1% (flatter than Fuego Flats) and Titans Grove is 0.7% so I wouldn’t be surprised if there were other errors kicking around in there. Also the Zwift KOM and Zwift KOM Reverse are both called “Zwift KOM” (no “Reverse” on the reverse segment). The information clearly has not been sanity checked.
The lead in is only 0.5km with 5m of elevation (2nd pic, the ride indeed only took 24km, not 31km to complete)
This is another case of free rides having a different lead-in from events. In an event there is 7.5km lead-in. I think this is the source of the difference, though it remains confusing and worth improving. Same issue as in this topic: