Edited to fix some mistakes, thanks for the corrections.

unless you mean DRAM specifically in favour of HBM for the datacentre/AI market (which is what they are doing)

Looks like it’s the opposite:

https://www.tweaktown.com/news/109259/samsung-shifts-focus-from-hbm-to-ddr5-modules-ddr5-ram-results-in-far-more-profits-than-hbm/index.html

The RoC doesn’t make much RAM, to my knowledge. It’s the RoK that does that. Samsung, Micron, and SK Hynix all have their own fabs.

The US hasn’t been competitive in RAM (edit: manufacturing, though there is one plant in Virginia) in something like 40 years. The PRC is working on catching up to the RoK. I hope they manage to export good RAM soon, because the Korean companies are all both cutting back on production (edit: expansion) to increase prices.

Also, the lone American company in the mix, which still manufactures most of its supply abroad, just killed off its consumer division entirely to focus on selling RAM to datacenters.