What grudges does Eason Chan have over Wu Bai?

No grudges.

Eason Chan and Wu Bai are friends. There is no bad blood or grudge between them. It's just that in "New Police Story" Wu Bai played Nicholas Tse's father, and the truck driver who killed Wu Bai was played by Eason Chan.

Eason Chan is a Chinese pop male singer, actor, and composer. He graduated from Kingston University in the United Kingdom. Wu Bai is a Taiwanese male singer, musician, guitarist, film and television actor, and photographer. He is a well-known Chinese rock singer and his representative work is "Norwegian Wood".