Yahweh claims to be burning in intense anger (v10). Moses says God is burning in anger (v11). Moses implores God to “Turn from your burning anger and relent [repent] from this disaster against your people”. God then repents of the “disaster that he had spoken of bringing”. If Moses’ statement, in context, is to implore God to change His mind, then the narrator’s phrase is an affirmation that this is exactly what happened.
Fisher, Christopher. God is Open: Examining the Open Theism of the Biblical Authors (Kindle Locations 1837-1841). Kindle Edition.