DAE 3D models often have flipped normals due to mismatched face winding order or coordinate system inconsistencies during export/import.
Normals use a face’s vertex winding order (clockwise vs. counterclockwise) to define the “front” side—if the modeling software’s export setting for this order doesn’t align with the DAE importer (e.g., a game engine), normals flip. Coordinate system differences (like Y-up in Blender vs. Z-up in some tools) can also reverse normals.
To fix this, recalculate normals in your 3D software (e.g., Blender’s “Recalculate Normals” option) or adjust export settings to match the target application.