Why is there no edge in step face?

Question

I use Open Cascade 7.5.0 to split patches.
I use freeCAD to view patches.
a face without an edge
There is a pile of intersecting patches, and I use BOPAlgo_ Builder to split them in order to obtain patches that do not intersect with each other. In some execution results of code execution, there are patches without edges as shown in the above figure. A normal patch is like the one shown in the following image.
a normal face with edges

May I ask what exactly the patches without edges are? How to detect such patches in code? What is the reason for this type of patches?

Compiler: VS2022 Community Edition
Programming language: C++
Third party library: Open Cascade 7.5.0
Operating system: Windows11

I have tried many methods, such as:

1. Use OCC to check if the patch is valid,then useless.
2. ShapeAnalysis:: IsOuterBound, then useless.
3. BRepCheck_ Invalid Analyzer,then useless
4. BRep_ Tool:: Triangulation determines whether to return null, no use.