Getting TypeError: Return value error on Magento 2

Need help,

getting

TypeError: Return value of MagentoFrameworkMailTransportInterfaceFactory::create() must be an instance of MagentoFrameworkMailTransportInterface, instance of SendinblueSendinblueModelTransport returned in /workspace/happyhottubs/vendor/magento/framework/Mail/TransportInterfaceFactory.php:53

Sendinblue di.xml file

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <!-- for override magento default Transport class with our custom module model-->
    <preference for="MagentoFrameworkMailTransport" type="SendinblueSendinblueModelTransport"/>
    <preference for="MagentoFrameworkMailTransportInterface" type="SendinblueSendinblueModelTransport"/>
</config>

Please help me how I can fix it on Sendinblue extension end.
Thanks