It's definitely vector-based. What you're seeing is that the vector tile gets rendered to a bitmap for display. If you zoom in quickly, rather than re-render th

It's definitely vector-based. What you're seeing is that the vector tile gets rendered to a bitmap for display. If you zoom in quickly, rather than re-render the bitmap over and over, it just scales the pre-rendered bitmap. When the new zoomed-in tile loads, then it re-renders that tile. Also, even though it's vector-based, there's still different tiles for different zoom levels. For example, with different levels of detail.