I honestly don't know
We do know that VK did want to stay initially, but I guess being a more traditional fullback and seeing Doyle come in on top of JJ while being required to play a role he's never played before but Doyle and JJ have, he probably saw his minutes at risk. At 19 with the Euros coming up I sort of understand the thought of wanting at least some guarantees. Enzo probably couldn't give him those because it would have taken VK a month or two to settle into the role and even then it wasn't a sure thing he would be a fit.