some suggestions why my "lego" mesh and textures looks so terrible in blender?

[miseon119]

I used nerf lego synthetic dataset. my nerf_lego.json is

{
    "ref_mesh": "data/nerf_synthetic/lego",
    "random_textures": true,
    "iter": 5000,
    "save_interval": 100,
    "texture_res": [ 2048, 2048 ],
    "train_res": [800, 800],
    "batch": 8,
    "learning_rate": [0.03, 0.01],
    "ks_min" : [0, 0.25, 0.0],
    "dmtet_grid" : 128,
    "mesh_scale" : 2.4,
    "laplace_scale" : 3000,
    "display": [{"latlong" : true}, {"bsdf" : "kd"}, {"bsdf" : "ks"}, {"bsdf" : "normal"}],
    "background" : "white",
    "out_dir": "nerf_lego"
}

my mesh result is:

What's wrong with my parameters? Is it that I used too small "dmtet_grid" value?

And "ethiopianHead_rescaled" dataset's result is also bad.