He looks like he's got an axe to grind. Better have a talk with him.

他看来是牢骚满腹，你最好找他谈谈。

《新英汉大辞典》

Often the author will have an axe to grind, leading to a one-sided commentary on issues and debates.

经常作者会有一把精心打磨的神斧，最终导致一种 对于问题和讨论的片面评论。

youdao

He may well have an axe to grind as well as a book to sell, but he is not the first person to call for Mr Ballmer to be replaced.

BBC: Microsoft's Steve Ballmer: Should he stay as boss?