The clickanywhere and hoveranywere is a cool new feature in Plotly 6.7, but it does't actually trigger a dash callback because the xvals and yvals are not included in the dcc.Graph clickData and hoverData props.

https://plotly.com/python/hover-text-and-formatting/

Emitting Hover and Click Events Anywhere in the Plot Area
New in 6.7

By default, hover and click events are only emitted when the cursor is over a trace. Set hoveranywhere or clickanywhere to True to emit these events anywhere inside the plot area, including over empty space: fig.update_layout(hoveranywhere=True, clickanywhere=True). The events carry the cursor's data coordinates, which is useful when building interactive callbacks (for example, in Dash) that need to respond to clicks on locations that don't correspond to a specific data point.

I'll create a PR to fix this