Incorrect stack/orientation for 1D charts

[kanitw]

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "A simple bar chart with embedded data.",
  "data": {
    "values": [
      {"b": 0},
      {"b": 10},
      {"b": 10},
      {"b": 10},
      {"b": 10},
      {"b": 20}
    ]
  },
  "mark": {"type": "bar", "orient": "horizontal"},
  "encoding": {
    "y": {"field": "b", "type": "quantitative"}
  }
}

The max value in the data is 20

But the domain is the sum of values, due to incorrect stacking logic.