The problem may be due to poor workmanship.

问题可能是出在拙劣的工艺上。

《柯林斯英汉双解大词典》

It's evident that the rust is due to poor workmanship.

事实表明生锈是因为粗糙的工艺。

youdao

The burnt cover is obviously because of poor workmanship in your factory because the end-user will not bother to open that box.

烧坏的外壳很明显是因为贵公司工厂的粗糙做工，因为用户是不会去开那个盒子的。

youdao

The workmanship was poor.

VOA: special.2009.02.22

"Made in Japan" equated to poor workmanship and cheap products.

BBC: Chinese New Year can help Beijing sell 'brand China'

Jane: If there is evidence of poor or dangerous workmanship Corgi do act.

BBC: Frontline Scotland graphic