Products are not updated via async API in Magento 2.4.6, though tasks are marked as succesful

When trying to update products via Magento async API, tasks are marked as succesfully accomplished, but products are not changed.

Almost all values under custom_attributes, including “tax_class_id” are not updated, except the “cost”. Standard attributes “price” and “qty” are always updated.

Payload example:

[
  {
    "product": {
      "sku": 1000,
      "custom_attributes": [
        {
          "attribute_code": "attribute1",
          "value": 10
        },
        {
          "attribute_code": "attribute2",
          "value": 20
        },
        {
          "attribute_code": "attribute3",
          "value": 30
        }
      ]
    }
  }
]