In the past photos, Tae-yeon's eyes were round, but in later photos, her eyes were obviously sharp and even felt elongated.

In the case of plain makeup (or nude makeup), you can see that Tae-yeon's eyes are a bit like single phoenix eyes+almond eyes.

However, most netizens think it's the eye makeup. In some periods, makeup will emphasize extremely thick eyeliner or thick false eyelashes. Artists' shapes will be different under different fashions, which is why many people look different without plastic surgery.