Got wrong encodedVariantAvailability and encodedVariantExistence from Storefront API

I use product query in Storefront API, and got many wrong value of encodedVariantAvailability and encodedVariantExistence fields.
I try 2025-01 and 2025-04, they all return wrong value.

In one case, I got "v1_1 " as encodedVariantExistence, but the product only has a default option with one default value.

{
    "encodedVariantAvailability": "v1_",
    "encodedVariantExistence": "v1_1",
    "options": [
      {
        "name": "Title",
        "optionValues": [
          {
            "name": "Default Title"
          }
        ]
      }
    ],
    "variants": {
      "nodes": [
        {
          "availableForSale": false,
          "currentlyNotInStock": false,
          "selectedOptions": [
            {
              "name": "Title",
              "value": "Default Title"
            }
          ],
          "title": "Default Title"
        }
      ]
    }
}

In document, the index of option value start from 0, but the value retrun from the API start from 1 sometimes.

Another case here:

The correct value of encoded_variant_availability and encoded_variant_existence should be v1_0-99.

I think this is a bug.

Can anyone confirm this?