Why the reduction rank is even

$$q^{-22}P_2(qt)=h(t)\prod_i\Phi_{k_i}(t)^{\gamma_i}$$

Weil + Tate

$$\rho(X_p^{\mathrm{al}})=\sum_i\gamma_i\deg\Phi_{k_i}=22-\deg h\in2\Z$$