Regarding the model, no matter how the edges are removed, it will deform

[xiaoweiqilv]

This is when exporting

[xiaoweiqilv]

Sorry, the image cannot be uploaded

[xiaoweiqilv]

This is before exporting

https://imgur.com/B6oNSbY

The import process is as follows

https://imgur.com/7QoV4PY

[MatzeH]

Looks like a mix of flipped normals and smooth edges. Try to break the edges do make them hard.

[DontDeleteThisAcc]

Could you clarify how I can fix the flipped normals or break the edges to make them hard? I'm facing a similar issue with model deformation during export, and I'm not sure where to start.

[MatzeH]

For flipping normals: best thing to do is to select all faces in edit mode and then select Mesh menu -> Normal -> Recalculate Outside

For making soft edges sharp: just mark the edges you want to be sharp in edit mode and then in the Edge menu select "Mark Sharp". Then they turn into turquoise lines.

[DontDeleteThisAcc]

Thankyou for this information.