Calligraphy, why should the last stroke of this word be written as a tick?

In calligraphy, this belongs to "leading belt" or "reflecting belt". The pen meaning between the upper and lower words echoes. Only running script or cursive script.

Ancient people usually wrote vertically. It is often the last stroke after writing a word, and the pen tip moves to the first stroke of the next word. When writing quickly, it will be brought out to the lower left in a "hook" shape. Some involve fine lines, called "ties". The three words in the picture below all have the relationship between reflection and tape:

One more thing: if you write from left to right, these two words will only be taken to the right.