Linea marcada en el cambio de estructura del objeto

Hi! I don’t know if anyone here has had this problem or knows how to solve it, this piece was looking very good, but when I went from making the complete base to making only the walls, this line was generated, the same thing happens to me with other parts of the same style, it is nothing related to the z axis, the printer is clean and with maintenance, it is just a matter of this style of objects.