I threw off what the same model looks like in roblox studio and blender
what could be the reason?
Normals might’ve been inverted, turn on Face Orientation in blender, if it’s red then it’s inverted.
While selecting the inverted faces in edit mode, Shift + N should fix the problem.
the normals in the blender are blue and moreover what is shown in the photo consists of 4 vertexes
while there are only 3 in the photo