Matthew Poole and continuators on 2 Chronicles 20:33

33 Howbeit, the high places were not taken away ; for as yet the people had not prepared their heart unto the God of their fathers .

Not fully nor universally; of which see on ch. 17. 6.

The Fault was not in Jehoshaphat, but in the People, who, though they did Worship the True God, yet would not be confined to the Temple, but for their own Conveniency, or from their Affection to their Ancient Custom chose to Worship him in the High Places: which Jehoshaphat was forced to connive at, lest those people being debarred from that dearly-beloved Practice, should fall into a Neglect of God and his Worship.