\], we get an isomorphism of $\overline{\bbF}_q$-algebras $$\xymatrix{ \sS_{\overline{\bbF}_q}:\cH_{\overline{\bbF}_q}^{\operatorname{sph}}\ar[r]^<<<<<{\sim} & \overline{\bbF}_q[V_{\mathbf{\whT},0}]^{W_0}=\big(\overline{\bbF}_q[X,Y,z_0^{\pm0}]/(XY)\big)^{W_0}