John Gill Commentary 2 Kings 15:28

"And he did that which was evil in the sight of Jehovah: he departed not from the sins of Jeroboam the son of Nebat, wherewith he made Israel to sin." — 2 Kings 15:28 (ASV)

And he did that which was evil in the sight of the Lord
Not only in committing the above crimes of usurpation and murder, but idolatry, and particularly the worshipping of the calves, hinted at in the text.