Radak: When Yeho'achaz became king, he thought to avenge his father's death via Pharaoh Necho. He invaded Egypt and struck them greatly. When he returned, Pharaoh Necho fought him in Chamas, and captured and incarcerated him - "va'Yilmad Litraf Teref Adam Achal" (Yechezkel 19:3, 6). Why would he incarcerate him, if there was no prior reason, i.e. [Yeho'achaz] fought him or invaded his land?! We find that [Pharaoh Necho] told Yoshiyah "I am not [coming to fight] against you today" (Divrei ha'Yamim II, 35:21). Rather, it seems like I said; Yechezkel's metaphor shows like this.

Malbim: First he removed him from his kingship and took him to Rivlah. Then he bound him in fetters, lest he rule again.

Radak: The Kesiv means while he ruled in Yerushalayim, for this short time, [Pharaoh Necho] took him. The pronunciation teaches that he removed him from kingship, because Yeho'achaz began to fight with him. Pharaoh Necho did not consider himself to be at fault for Yoshiyah's death, for Pharaoh Necho had not come to fight him (he only wanted to pass through Eretz Yisrael). Even so, Hashem avenged him, like it is written ¹ .

Kli Yakar: Once Pharaoh Necho killed Yoshiyah, he inherited the kingship; no one in Yerushalayim would raise his hand against him. Bi'Mloch (once Yeho'achaz became king), Pharaoh Necho incarcerated him. We pronounce it mi'Mloch, for this is the reason (he became king without permission; this was rebellion). It is also the reason for the monetary punishment that he imposed.

Kli Yakar: Refer to 23:33:3:2.

Malbim: It is because they picked the younger to be king before the older; Pharaoh Necho made the proper (older) one king.