God was acting for a different purpose than Jehu was. Jehu was doing all this to strengthen himself as king. Both purposes were being accomplished!
V.29-30 But God saw exactly what the heart of Jehu was like.
V.31-36 You would think that Jehu would have learned something about God from all these things, but no. He was just like millions today, thinking that God doesn’t notice everything, even the heart of the man who was carrying out His purposes.