Albert Barnes Commentary Ezekiel 42:5

"Now the upper chambers were shorter; for the galleries took away from these, more than from the lower and the middlemost, in the building." — Ezekiel 42:5 (ASV)

Render: And the upper chambers were shortened, for galleries extended from them, from the lower and from the middle-most, chambers, of the building. The building rose in terraces, as was usual in Babylonian architecture, and so each of the two upper stories receded from the one below it.