Tested this branch on what I was doing that highlighted the issue and it works now :)

When axes are swapped, there's an issue with scaling it seems

#test-case({
  plot.plot(
    size: (10,6), 
    // y-max: 100,
    {
      plot.add(domain: (20, 30), x=>x, mark: "x", axes:("y", "x"))
    }
  )
})

#test-case({
  plot.plot(
    size: (10,6), 
    // y-max: 100,
    {
      plot.add(domain: (20, 30), x=>x, mark: "x", axes:("y", "x"))
    }
  )
})

Good catch. Fixed.

This PR introduces new problems, so I suggest closing this in favor of #81 which solves the problem in a better way.