The ESV renders Genesis 31:42 like so (emphasis mine):
If the God of my father, the God of Abraham and the Fear of Isaac, had not been on my side, surely now you would have sent me away empty-handed. God saw my affliction and the labor of my hands and rebuked you last night.
It seems the title “Fear of Isaac” is translated by the ESV as a name for God. However other translations like the KJV eschew the capitalization, such that it almost reads as if Jacob’s dread of Isaac’s anger was instrumental in Jacob’s success or some such thing. Is “the fear of Isaac” a title/name for God? Or something else? What does this phrase mean?