[Magento 2.4.7] Product import returns errors after Magento upgrade

[Arkadij-RS]

Hello,

We have recently upgraded our Magento version from 2.4.6 to 2.4.7 and product imported stopped working.
Also during the upgrade we updated FireGento_FastSimpleImport2 to the latest 2.1.0 version.
The business logic imports product data with external system regularly by cron job. After we have released the new
versions we can see only errors in cron logs and no successful runs.

Old versions:

• PHP: 8.1
• Magento: "2.4.6-p3"
• "firegento/fastsimpleimport": "1.3.4"

New versions:

• PHP: 8.1
• Magento: 2.4.7-p3
• "firegento/fastsimpleimport": "2.1.0"

Errors:

1. URL key for specified store already exists.
2. Warning: Undefined array key "apply_to" in
   /domains/corneyandbarrow.com/deployer/releases/116/vendor/magento/module-catalog-import-export/Model/Import/Product/Type/AbstractType.php
   on line 233
3. Please enter a correct entity model.
4. Warning: Trying to access array offset on value of type null in /domains/corneyandbarrow.com/deployer/releases/116/vendor/magento/module-catalog-import-export/Model/Import/Product.php on line 2437

To make sure that the upgrade is the cause of a problem we have reverted back to Magento 2.4.6 in the staging environment and all product imports worked well. There is no difference within the data importing from external system.