The market is hedging ahead of Micron's earnings report, after all, many people have made money earlier, so taking profits and securing gains is normal.

If Micron's earnings hint at a peak in price increases, an early end to supply and demand tightness, or cloud service providers' capex entering a digestion phase, or FY Q4 guidance being cautious, then this directly hits the core bullish logic of "supply and demand gap" that Hynix relies on, which could be a bit risky.
If the decline is purely because the market's expectations for Micron were too high and this led to a drop in stock price that transmits to Hynix, then it might actually be a buying opportunity.
This morning, I took profits on Hynix first, waiting for a chance to re-enter later.
Keep in mind that with leveraged ETFs and record-breaking margin positions, the fragile structure makes it easy to get trampled during a reversal, so I hope to catch some bloodied chips.