True. The FreeHand + feature came with the 2022.0 release. It appears that since then the SHIFT polyline draw mode was removed. See this topic (which I never noticed until now):
The object drawn with the Freehand tool’s base mode is a curve made up with connected edge objects. The curve is singly selectable with the Select tool.
What we can say is that the Freehand tool has been simplified to remove the polyline SHIFT feature since v2022.0.
The existence of Polyline3d objects was a well kept “secret” as the tool’s SHIFT polyline mode was not explained on the status bar with other modifiers.
The true Polyline3d objects always have been exposed to the C API. But never to the Ruby API.
Others and I have asked for a dedicated Polyline tool to create non-geometric 3D pathways that do not effect edges or faces. The SketchUp team’s responses have been mixed, some saying that true polylines will make a comeback, others saying polylines are goners.