'hovercompare' modebar button does not retain hovermode y

MWE:

const data = [
  {
    x: [1, 2, 3, 4],
    y: [10, 15, 13, 17],
    type: 'scatter'
  },
  {
    x: [1, 2, 3, 4],
    y: [10, 13, 15, 17],
    type: 'scatter'
  }
];

const layout = {
  hovermode: 'y',
  modebar: { add: ['hoverclosest', 'hovercompare'] }
};

Plotly.newPlot('myDiv', data, layout);

One might expect that if the hoverclosest button is clicked and then hovercompare after, it should return to the hover comparison by y values, as initially set, but instead, it switches to the default comparison by x values. If there is a workaround, that would also be helpful.

Start by reproducing the supplied MWE with hovermode set to y and the hoverclosest and hovercompare modebar buttons enabled. Trace how those buttons change hovermode, then verify that switching back to hovercompare preserves comparison by y values rather than reverting to x values.