To which god does Leviticus 18:21 forbid Israel to sacrifice their children?

Answer: Molech

Leviticus 18:21 forbids giving children to be sacrificed to Molech, and Leviticus 20:2 made it a capital crime.

“You must not give any of your children to be sacrificed to Molech, for you must not profane the name of your God. I am the LORD. “Tell the Israelites, ‘Any Israelite or foreigner living in Israel who gives any of his children to Molech must be put to death. The people of the land are to stone him.”— Leviticus 18:21, 20:2 (BSB)