TLDR: - Trade war because of SK following US directive to install THAAD, which at surface is aimed at NK, but the real target, at least from US perspective, is at China.

- Increasing competition from Chinese firms

- US waging sanctions and trade ban tech war, and the SK firms following US trade restrictions voluntarily or involuntarily. This has made nearly all Chinese sectors examine their supply chain for tech and goods that might be banned by a stroke of pen from Washington and switching to more reliable alternatives. This has the surprising effect of improving competitiveness of many Chinese firms, especially in the areas SK firms are good at. Leading to more number 2