How did you import the mesh to Roblox?
What type of file name (like obj.) did you use?
I’m guessing you have the wrong TextureID saved, or you used the headphones mesh and then imported the pirate hat MeshID into it without importing the TextureID.
set “Show Backface” to OFF
set “Backface Culling” to ON
These settings can be found Shader Editor, but you can go to the Material Properties tab in the Properties window with the hats selected.
If you’re still finding some strange hat issues, you might want to do this with all the materials in the scene.