I would bet this is actually multiple people sharing IP.

Many countries and ISPs that lack IPv4 pool many people under single public IP and then redistribute later to individual. Very rare at ISP level in NA but very common in SEA. Though VPNs also give the same effect. And there's probably no country in earth more lacking in IP assignments than North Korea. The entire country shares measly four of /24 assignments which means roughly 1024 IPs for the entire country including all of infrastructure equipments that need IP assignments.

So likely a pool of people from NK show up under the same IP. They do physically connect through China entirely. But these few IP assignments that's assigned to NK should show up as NK instead of China.

Speaking of VPNs, some VPN companies claim they have NK IP. Never tried myself, but if true people using that VPN and connecting to steam would also show up as a dot there. So they may not even be North Koreans.