Pretty sure they are screen space reflections, a commonly-used feature of UE4, usually associated with water reflections.
They look amazing, but the downside is they disappear towards the edges of the screen, and they disappear if you tilt the camera far enough to remove the reflection's light source from view e.g. ceiling lights. Usually there's a less accurate "backup" reflection in a lot of games, but that doesn't seem to be the case with Shenmue III.