Why is sati sampajāno mentioned in the 3rd jhana?

MN 4 says: > And with the fading away of rapture, I entered and remained in the > third absorption, where I meditated with equanimity, mindful and > aware, personally experiencing the bliss of which the noble ones > declare, ‘Equanimous and mindful, one meditates in bliss.’ > > Pītiyā ca virāgā upekkhako ca vihāsiṁ, sato ca sampajāno sukhañca > kāyena paṭisaṁvedesiṁ; yaṁ taṁ ariyā ācikkhanti: ‘upekkhako satimā > sukhavihārī’ti tatiyaṁ jhānaṁ upasampajja vihāsiṁ. Sujato has subjectively opined here: > The emotional response to bliss matures from the subtle thrill of > rapture to the poise of equanimity. Mindfulness is present in all > states of deep meditation, but with equanimity it becomes prominent. Why do we personally think sati sampajāno is mentioned in the 3rd jhana?