Charles Ellicott Commentary Lamentations 5:22

"But thou hast utterly rejected us; Thou art very wroth against us." — Lamentations 5:22 (ASV)

But you have ... —The Authorized Version represents the mourner as falling back from the hopeful prayer into the depths of despair. For “but” we should, however, read unless. The hypothesis of utter rejection is just stated as the only thing that could prevent renewal and restoration, and it is stated as per impossible; God has not rejected, and therefore He will renew.

It may be noted that in Synagogue use, and in many manuscripts, Lamentations 5:21 is repeated after Lamentations 5:22, so that the book might not end with words of such terrible significance. The same practice was followed for the last verse of Isaiah, Ecclesiastes, and Malachi.