Horrible, visible connections between meshes

Thanks ZacD, interesting post.

I changed some options in my normal map, it is better but there is something very wrong when i change metallic to 1.

Metallic off - small bleeding but it’s ok
b5bdfd33c102a72853f6539c1b252ac0ca0d17a1.jpeg

Metallic on - WTF? (Metallic -1 (whole texture- no mask) Roughness - none)
0a7ed1fd33c070685e6683e35e30f8733f88e53f.jpeg

i don’t understand what is going on.