Export fbx changed the origin rest pose

Artwork Animations
,
1

I download a .fbx from mixamo, import it with blender. However, when export to a new fbx from blender, the rest pose is been changed. If export to .bvh or .glb, the rest pose is same as origin file. I tried both in GUI and with python script, the conclusion is the same. I wonder why it is? Look forward to your help.

this is the origin rest pose

T-pose

this is the rest pose after exporting (become a frame of the animation)

after exporting to fbx

below is my python script

armature_name = "Armature"

bpy.ops.import_scene.fbx(filepath=file, axis_forward="-Z", axis_up="Y")


# print(bpy.data.objects["Geometry"])
# print(bpy.data.armatures["Geometry"])

bpy.ops.object.select_all(action='DESELECT')
bpy.data.objects[armature_name].select_set(True)
if len(bpy.data.objects[armature_name].children) > 0:
    bpy.data.objects[armature_name].children[0].select_set(True)


bpy.ops.export_scene.fbx(filepath="m01_test.fbx",
                         use_selection=True, add_leaf_bones=False)