Ordinal dates on x-axis off by one when using errorband marks

[Prestaul]

Bug Description

When displaying utc dates on the x-axis using type: ordinal, dates are rendered correctly unless we add an errorband mark. With an errorband mark the dates on the x-axis are one day early.

This is a minimal reproduction where the x-axis label should be for Jan 1st but it appears as Dec 31st unless you set the x encoding type to temporal or remove the errorband layer:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [{"date": "2025-01-01", "value": 1 }]
  },
  "encoding": {
    "x": {
      "field": "date",
      "type": "ordinal",
      "timeUnit": "utcyearmonthdate"
    },
    "y": {"field": "value", "type": "quantitative"}
  },
  "layer": [
    { "mark": "line" },
    { "mark": "errorband" }
  ]
}

Checklist

• I checked for duplicate issues.

[Prestaul]

I still believe this is a bug, but I did find a workaround. By NOT using a utc time unit, and appending T00:00:00 on each date, you can force it to treat each date as local time.

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [{"date": "2025-01-01T00:00:00", "value": 1 }]
  },
  "encoding": {
    "x": {
      "field": "date",
      "type": "ordinal",
      "timeUnit": "yearmonthdate"
    },
    "y": {"field": "value", "type": "quantitative"}
  },
  "layer": [
    { "mark": "line" },
    { "mark": "errorband" }
  ]
}