In the following PG, floor1 is flickering after adding a standard material, this is present in version 4, 5 and 6. Is it related to serialization?How to fix flickering？
It looks like z-fighting.
You should try to open your model in a DCC tool and see if you can spot coplanar triangles. If you generated the serialization from an existing PG, then it would help to see what this PG is doing.
The model can be correctly rendered with pbr material.
In fact the problem is really z-fighting. Your material has backface culling disabled, so there’s z-fighting between the font and back faces.
You will get the same problem in your PG with the PBR material if you disable backface culling: