How to get variable mode setting for the current page

In my plugin I need to retrieve the variable modes that have been set by the user for the current page - but I don’t see any API for doing that.

On other node types I can use resolvedVariableModes and explicitVariableModes to get the modes, but on page nodes these are both undefined.

I could search for a top level node in the page with no explicit mode settings, and then derive the page setting from that, but that’s a pretty roundabout way of getting to it.

Any ideas? Is there something I am missing in how to do this?