When using MapboxLayers, the cursor stays "grab" and doesn't change to "grabbing" on drag. The cursor style cannot be explicitly modified by map.getCanvas().style.cursor = /* style */, either.
See https://deck.gl/showcases/gallery/mapbox-layer.
My workaround is to set my own getCursor function after adding a MapboxLayer to the map instance so that is doesn't modify the existing style.
map.__deck.props.getCursor = () => map.getCanvas().style.cursor;
You can try Use a Layer from an Existing Deck's Layer Stack which will allow you to set Deck props.
Or you can do:
<DeckGL getCursor={() => 'inherit'} />
This will inherit the same cursor as Mapbox.
Most helpful comment
My workaround is to set my own
getCursorfunction after adding a MapboxLayer to the map instance so that is doesn't modify the existing style.