How could you tell? Not trolling, genuinely curious.
Says so in their twitter bio.
For this piece specifically, the one thing that stands out is that her tokin has too many tassels. It should only have two, but seems to have four. For the Nareko one, her earrings are melting together.
Checking the artist's history, they seem to just suddenly start posting fully completed works about a year ago after having the account for two years, they post art daily, and sometimes post multiple pieces on the same day. There's AI artifacts all over them, too. Look at the cat and its reflection here.
For this piece specifically, the one thing that stands out is that her tokin has too many tassels. It should only have two, but seems to have four. For the Nareko one, her earrings are melting together.
Dang, you've got good eyes! And yeah, I didn't think of looking in their bio, and I admit I wouldn't have thought of translating it even if I did, derp. I learned something new today, thanks!