This is a kind of writing virtue, which has existed since ancient times. It does not affect recognition and reading, just like many words have variant forms. It can be horizontal or not, both of which are correct. Now it is famous: Quanjude has been missing a horizontal character on the plaque in order to maintain its original historical appearance. Couplets:
A duck, 146 years old, has a long history and a lingering fragrance.
The lack of more than one does not hinder the flavor of roast duck. There is no more than one, and virtue is still virtue.