Use service contracts to persist entities in favour of Magento\Email\Model\Template::load() method

Use service contracts to persist entities in favour of Magento\Email\Model\BackendTemplate::delete() method

Method Magento\Email\Controller\Adminhtml\Email\Template\Preview::execute() should return Magento\Framework\App\ResponseInterface|Magento\Framework\Controller\ResultInterface but return statement is missing.

Use service contracts to persist entities in favour of $this(Magento\Email\Model\AbstractTemplate)::load() method

$this(Magento\Email\Model\BackendTemplate)::_getResource() is deprecated. Use Resource Models directly

$this(Magento\Email\Model\Template)::_getResource() is deprecated. Use Resource Models directly

Use service contracts to persist entities in favour of $this(Magento\Email\Model\Template)::load() method

Return type mixed of method Magento\Email\Model\Template\Config\FileIterator::current() is not covariant with tentative return type mixed of method Iterator::current().

Method Magento\Email\Setup\Patch\Data\FlagLegacyTemplates::apply() should return $this(Magento\Email\Setup\Patch\Data\FlagLegacyTemplates) but return statement is missing.

Setter methods like Magento\Email\Block\Adminhtml\Template\Edit::setTemplate() are deprecated in Block classes, use constructor arguments instead