Preconditions

1. Magento: 2.4.0
2. PHP: 7.3.22
3. MySQL: MariaDb:10.4
4. mageplaza/magento-2-blog-extension: 3.1.3
5. mageplaza/module-blog-graphql: 1.0.0

Steps to reproduce

1. Install latest mageplaza/magento-2-blog-extension and mageplaza/module-blog-graphql
2. Add some example products
3. Filter regular Magento products with the following GraphQL query:

query {
  products(
    pageSize: 10
    currentPage: 1
    filter:  {
      sku: {
        eq: "24-MB01"
      }
    }
  ) {
    total_count
    items {
      name
    }
  }
}

Expected response

{
  "data": {
    "products": {
      "total_count": 1,
      "items": [
        {
          "name": "Joust Duffle Bag"
        }
      ]
    }
  }
}

Actual response

{
  "errors": [
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "products"
      ]
    }
  ],
  "data": {
    "products": null
  }
}

Error

The actual error in debug.log is:

main.ERROR: Attribute not found in the visible attributes list {"exception":"[object] (GraphQL\\Error\\Error(code: 0): Attribute not found in the visible attributes list at /var/www/html/vendor/webonyx/graphql-php/src/Error/Error.php:174, LogicException(code: 0): Attribute not found in the visible attributes list at /var/www/html/vendor/magento/framework/GraphQl/Query/Resolver/Argument/AstConverter.php:103)"}

But this (eventually) traces back to Magento/Framework/GraphQl/Query/Resolver/Argument/FieldEntityAttributesPool.php at line 39.

This line should return an array of product attributes in which we can filter by, but instead, the attributesInstances['products'] resolver is overridden by this projects etc/di.xml file on line 42.

This override causes getEntityAttributesForEntityFromField to return:

Array (
   [0] => name
   [1] => products
   [2] => sku
)

When it should return an array similar to:

Array
(
    [name] => Array
        (
            [type] => String
            [fieldName] => name
        )
[...etc]
)

Temporary fix

If someone needs a temporary fix, you can re-override that di by adding

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<type name="Magento\Framework\GraphQl\Query\Resolver\Argument\FieldEntityAttributesPool">
        <arguments>
            <argument name="attributesInstances" xsi:type="array">
                <item name="products" xsi:type="object">
                    Magento\CatalogGraphQl\Model\Resolver\Products\FilterArgument\ProductEntityAttributesForAst
                </item>
            </argument>
        </arguments>
    </type>
</config>

To your own [Vendor]\[Module]\etc\di.xml file.

Actual fix

I think lines 42-44 of etc/di.xml may have been included by mistake? I'm happy to submit a PR for this but I wanted to check that removing lines 42-44 in etc/di.xml won't cause other issues.