There is a bug with continuous zoom (view.constraints.snapToZoom = false). It's sometimes impossible to zoom in to max scale (or zoom out to min scale) using mouse wheel.
Codepen sample: https://codepen.io/mateusz-olsztyski/pen/QWBWxmN
I am not sure if this is a bug.
The mouse wheel scrole works on a ratio of scale based on the initial scale set. Here is a table illistrating the zoom scales and there ratio to the initial zoom scale. If I use the Shift + rectangle on the map to zoom right in to the max scale I am able to zoom to the max scale. Scrolling out from there shows the zoom scales according to the mouse scrole ratio.
zoom: 19 represents the scale of 1128.497176 which is one of the basemap LODs.