Illustration of the unsteady phase. Left panel: meridional cut of the norm of the poloidal magnetic field. The black dots show the position of 5 control points located on different field lines. In the other two panels, the temporal evolution of these points is followed during 20τ_Ap, both for the toroidal field B_ϕc (middle panel) and the normalised differential rotation ΔΩ_c/Ω₀ (right panel). The parameters are E = 10⁻⁴, P_r(N₀/Ω₀)² = 10⁴, Re_c = 1, L_u = 5 × 10⁴, and P_m = 10² (run D5 of Table 1).