"Learning Late Letters", originally written in Vietnamese by Nguyễn Hoàng Quyên, was one of the winners of the 2020 Words Without Borders Academy of Americans Poets Poems in Translation Contest. But, looking at the text of this short piece of literature, it doesn't fit with what I (having read mostly English poetry) would think of as a "poem". Rhyme and rhythm could be lost in translation, of course, but there are no lines in this piece! My instinct would be to call it short prose instead, but then I know nothing about Vietnamese poetry and its norms.
What defines "poetry" in Vietnamese literature, or why is this particular work called a poem?