This paper is about Euler characteristics of moduli spaces of m-Kronecker quivers. You have “ripples” and “a straight line” in Figs. 3 and 4.
So Okada: On Douglas' conjecture for $m$-Kronecker quivers https://arxiv.org/abs/2611.04862 https://arxiv.org/pdf/2611.04862 https://arxiv.org/html/2611.04862