Several months ago, I was doing ping geolocation on a bunch of VPN servers. To see if they're actually located where claimed. I looked at several AirVPN servers, claimed to be in Hong Kong. Based on data from hundreds of probes, they did in fact seem to be in Hong Kong.

However, minimum(rtt) was ~300 msec for probes in several mainland locations, some <100 km from Hong Kong. Why might that have been?