Taipei in January: mean 16.3°C, absolute humidity 10.9.
Seoul in January: mean −2.6°C, absolute humidity 2.3.

Taipei holds 4.7 times as much. A four-hour flight, and nearly 80% of the water in the air is gone.

And not only outdoors. Indoor heating dries air the same way air conditioning does. So it isn't 'cold outside, fine back at the hotel'. It's twenty-four hours a day in extremely dry air.

Why the routine you packed won't be enough

What you use at home was formulated on the assumption that the air helps hold water in. In Seoul that assumption is gone, and the same bottle simply underperforms — it didn't get worse, its default conditions disappeared.

The damage usually shows on day two or three: the first days run on the skin's own reserves, and when those are spent it starts flaking, stinging, and refusing makeup.

The four levers

1. QuantityOne of the settings that calls for more — starting on day one, not after it goes wrong. Repairing on day three is chasing.
2. OrderThe occlusive layer goes last and cannot be skipped. At home it's optional. Here it's the whole point.
3. TimingIndoor heating does most of its damage across the eight hours you're asleep. The evening round matters more than the morning one.
4. IntervalWalking from below-freezing into a heated room, your face takes the sharpest swing in the building. Let it come back up before you touch it.

What goes in the suitcase isn't decided by what you're used to.
It's decided by how much water is in the air where you're going.