Hi. This is a bug report, for a glitch that appears to be in the back-end handling of uploaded GPS traces.
It affects this area:
https://www.openstreetmap.org/#map=16/37.6536/126.9679&layers=G
When you enable “Public GPS Traces”, you see many unexpected lines joining trace points that really shouldn’t be connected. I suspect there’s a timestamp problem with some of the traces, and unrelated points from different traces are assumed to be related, and thus are drawn connected.
The same effect happens in JOSM when I try to edit the area. Download map data, download traces. I had to find the setting for “points only” to make the traces usable; otherwise the artefacts badly obscured the actual traces.
I know there’s probably a more appropriate place in the maze of OSM communication channels to report this, but for now, here it is.