The behavior of how simple edges are snapped at mid-span when snapping is enabled during GN building has changed at 10.0.
In 9.3 the behavior was are simple edges NOT snapped within the cluster tolerance at mid-span vertexes and vertexes are NOT inserted where needed to snap to, and no connectivity established for either condition.
As part of the reworking of the GN creation code to provide a more scalable solution, we had to change how this aspect of the snapping model behaves. So, in 10.0 simple edges are snapped within the cluster tolerance at mid-span vertexes or a vertex is inserted and snapped to, but no connectivity is established for either condition.