Ill-posedness issue on a multidimensional chemotaxis equations in the critical Besov spaces

In this paper, we aim to solving the open question left in [Nie, Yuan: Nonlinear Anal 196 (2020); J. Math. Anal. Appl 505 (2022)) and Xiao, Fei: J. Math. Anal. Appl 514 (2022)]. We prove that a multidimensional chemotaxis system is ill-posedness in $\dot{B}{2d, r}^{-\frac{3}{2}} \times\big(\dot{B}{2d, r}^{-\frac{1}{2}}\big)^{d}$when$1\leq r<d$ due to the lack of continuity of the solution.