denistrator/Block CustomProductInfoTab.php

## Block CustomProductInfoTab.php
<?php
/**
 * Copyright
 */

namespace Vendor\Module\Block;

use Magento\Cms\Model\ResourceModel\Block\CollectionFactory;
use Magento\Framework\DataObject;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\View\Element\Template;
use Magento\Store\Model\StoreManagerInterface;

class CustomProductInfoTab extends Template
{
    const CUSTOM_PRODUCT_INFO_TAB_CMS_BLOCK_ID = 'product_info_custom_tab';

    /**
     * @var StoreManagerInterface $storeManager
     */
    protected $storeManager;

    /**
     * @var CollectionFactory
     */
    protected $entityCollectionFactory;

    public function __construct(
        Template\Context $context,
        StoreManagerInterface $storeManager,
        CollectionFactory $collectionFactory,
        array $data = []
    ) {
        $this->storeManager = $storeManager;
        $this->entityCollectionFactory = $collectionFactory;
        parent::__construct($context, $data);
    }

    /**
     * Object data getter
     *
     * If $key is not defined will return all the data as an array.
     * Otherwise it will return value of the element specified by $key.
     * It is possible to use keys like a/b/c for access nested array data
     *
     * If $index is specified it will assume that attribute data is an array
     * and retrieve corresponding member. If data is the string - it will be explode
     * by new line character and converted to array.
     *
     * @param string $key
     * @param string|int $index
     * @return mixed
     */
    public function getData($key = '', $index = null)
    {
        if ($key === 'title' && $customCmsBlockTitle = $this->getCustomCmsBlockTitle()) {
            return $customCmsBlockTitle;
        }

        return parent::getData($key, $index);
    }

    /**
     * @return string|null
     */
    public function getCustomCmsBlockTitle()
    {
        $block = $this->getCustomCmsBlock();

        if (!$block || !$block->getData('is_active')) {
            return null;
        }

        return $block->getData('title');
    }

    /**
     * @return DataObject|null
     */
    public function getCustomCmsBlock()
    {
        $entityCollection = $this
            ->entityCollectionFactory->create()
            ->addFieldToFilter('identifier', self::CUSTOM_PRODUCT_INFO_TAB_CMS_BLOCK_ID)
            ->addStoreFilter($this->getStoreId());

        return new DataObject($entityCollection->getData()[0]);
    }

    /**
     * @return int
     */
    public function getStoreId()
    {
        $storeId = 0;

        try {
            $storeId = $this->storeManager->getStore()->getId();
        } catch (NoSuchEntityException $e) {
        }

        return $storeId;
    }
}

## view frontend layout catalog_product_view.xml
<?xml version="1.0"?>
<!--
/**
 * Copyright
-->
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <body>
        <referenceBlock name="product.info.details">
            <block name="product.info.custom.tab" class="Vendor\Module\Block\CustomProductInfoTab"
                   template="Magento_Theme::html/container.phtml" group="detailed_info" after="-">
                <block class="Magento\Cms\Block\Block" name="product.info.custom.tab.cms.block">
                    <arguments>
                        <argument name="block_id" xsi:type="string">product_info_custom_tab</argument>
                    </arguments>
                </block>
            </block>
        </referenceBlock>
    </body>
</page>
	<?php
	/**
	* Copyright
	*/

	namespace Vendor\Module\Block;

	use Magento\Cms\Model\ResourceModel\Block\CollectionFactory;
	use Magento\Framework\DataObject;
	use Magento\Framework\Exception\NoSuchEntityException;
	use Magento\Framework\View\Element\Template;
	use Magento\Store\Model\StoreManagerInterface;

	class CustomProductInfoTab extends Template
	{
	const CUSTOM_PRODUCT_INFO_TAB_CMS_BLOCK_ID = 'product_info_custom_tab';

	/**
	* @var StoreManagerInterface $storeManager
	*/
	protected $storeManager;

	/**
	* @var CollectionFactory
	*/
	protected $entityCollectionFactory;

	public function __construct(
	Template\Context $context,
	StoreManagerInterface $storeManager,
	CollectionFactory $collectionFactory,
	array $data = []
	) {
	$this->storeManager = $storeManager;
	$this->entityCollectionFactory = $collectionFactory;
	parent::__construct($context, $data);
	}

	/**
	* Object data getter
	*
	* If $key is not defined will return all the data as an array.
	* Otherwise it will return value of the element specified by $key.
	* It is possible to use keys like a/b/c for access nested array data
	*
	* If $index is specified it will assume that attribute data is an array
	* and retrieve corresponding member. If data is the string - it will be explode
	* by new line character and converted to array.
	*
	* @param string $key
	* @param string\|int $index
	* @return mixed
	*/
	public function getData($key = '', $index = null)
	{
	if ($key === 'title' && $customCmsBlockTitle = $this->getCustomCmsBlockTitle()) {
	return $customCmsBlockTitle;
	}

	return parent::getData($key, $index);
	}

	/**
	* @return string\|null
	*/
	public function getCustomCmsBlockTitle()
	{
	$block = $this->getCustomCmsBlock();

	if (!$block \|\| !$block->getData('is_active')) {
	return null;
	}

	return $block->getData('title');
	}

	/**
	* @return DataObject\|null
	*/
	public function getCustomCmsBlock()
	{
	$entityCollection = $this
	->entityCollectionFactory->create()
	->addFieldToFilter('identifier', self::CUSTOM_PRODUCT_INFO_TAB_CMS_BLOCK_ID)
	->addStoreFilter($this->getStoreId());

	return new DataObject($entityCollection->getData()[0]);
	}

	/**
	* @return int
	*/
	public function getStoreId()
	{
	$storeId = 0;

	try {
	$storeId = $this->storeManager->getStore()->getId();
	} catch (NoSuchEntityException $e) {
	}

	return $storeId;
	}
	}
	<?xml version="1.0"?>
	<!--
	/**
	* Copyright
	-->
	<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
	<body>
	<referenceBlock name="product.info.details">
	<block name="product.info.custom.tab" class="Vendor\Module\Block\CustomProductInfoTab"
	template="Magento_Theme::html/container.phtml" group="detailed_info" after="-">
	<block class="Magento\Cms\Block\Block" name="product.info.custom.tab.cms.block">
	<arguments>
	<argument name="block_id" xsi:type="string">product_info_custom_tab</argument>
	</arguments>
	</block>
	</block>
	</referenceBlock>
	</body>
	</page>