a sign of tanka poem
A scholar of Japanese literature from Bulgaria, Tzvetana Kristeva says in "Thoughtful Japanese" that it means that while passing from person to person, it became impossible to identify who was the composer, not that the composer is unknown. And also, he says that it had the effect of shifting the focus from the background of the tanka poem to the expression itself. When the discussion went well in the meeting, everyone looks at each other, saying, "Who did say so first?"
"November 5 2019
from “Oriori no Kotoba” by Kiyokazu Washida, The Asahi Shimbun"