Why are Koreans called "sticks"? What are the allusions?

There are two more credible statements.

First, when Japan occupied the Northeast, most of the low-level security guards were Koreans. Because they are also second-class citizens, the Japanese don't trust them, they don't have guns, they just send a stick. However, these Koreans like to bully China people and beat China people with batons at every turn, so people call these Korean security guards Koryo sticks.

Second, bonzi generally refers to Koreans. Korea used to be Korea, which is rich in ginseng. Ginseng is nicknamed Bonzi in China. So there is a habit of addressing Koreans with Korean sticks.