Repeater field returning false instead of [] when empty

This is an excerpt of one of our acf-json files:

{
  "key": "field_1111,
  "label": "Filters",
  "name": "filters",
  "type": "repeater",
  "sub_fields": [
    {
      "key": "field_2222",
      "label": "Key",
      "name": "key",
      "type": "select",
      "choices": {
        "foo": "Foo",
        "bar": "Bar"
      },
      "default_value": [], // <-- this changed to false after ACF Pro update from 5.8.7 to 5.12.3
      "allow_null": 0,
      "multiple": 0,
      "return_format": "value",
    }
  ]
}

And sure, this makes sense. The sub_field "key" is a single select so it should return false when nothing is selected. In case of multiple select, an empty array makes more sense.

But: In case the parent repeater field "filters" is empty (= no items inside the repeater) ACF Pro will return false for this field. Expectation should still be an empty array for an empty repeater. Right?

Reproduce the behavior with the provided ACF JSON configuration, comparing ACF Pro 5.8.7 and 5.12.3 when the filters repeater has no items. Verify that an empty repeater returns [] while an empty single-select sub-field still returns false.