M2.4 – Trying to access array offset on value of type null – bin/magento app:config:import

Magento 2.4.3 with config data is stored into config.php using app:config:dump

When changing a setting in config.php and running:

bin/magento app:config:import

I am getting the following error message:

Import failed: Notice: Trying to access array offset on value of type null in /vendor/magento/module-cron/Model/Config/Backend/Product/Alert.php on line 78 app:config:import failed. See previous output.

I have tried having nothing in config.php relating to productalert_cron, I have also tried it with the following.

 'productalert_cron' => [
                'frequency' => 'D',
                'time' => '01,00,00',
                'error_email_identity' => 'general',
                'error_email_template' => 'catalog_productalert_cron_error_email_template',
            ],

In the DB (core_config_data), there is the following record:

Any ideas on how to fix it?