Could not save child: "Unknown entity type: Magento\Bundle\Model\Selection\Interceptor requested"

[faradey]

Preconditions and environment

• Magento version 2.4.6, 2.4.7, 2.4.8

Steps to reproduce

1. Create a module MyCompany/MyModule.

2. Add a plugin in the app/code/MyCompany/MyModule/etc/adminhtml/di.xml file:

   <type name="Magento\Framework\Model\AbstractModel">
       <plugin name="MyCompany\MyModule\Plugin\MagentoFramework\Model\AbstractModel"
               type="MyCompany\MyModule\Plugin\MagentoFramework\Model\AbstractModel"
               disabled="false" sortOrder="1000"/>
   </type>

3. Create the class MyCompany/MyModule\Plugin\MagentoFramework\Model\AbstractModel:

   <?php
   
   namespace MyCompany\MyModule\Plugin\MagentoFramework\Model;
   
   class AbstractModel
   {
       /**
        * @param \Magento\Framework\Model\AbstractModel $subject
        * @param mixed $result
        * @return \Magento\Framework\Model\AbstractModel
        */
       public function afterBeforeSave(
           \Magento\Framework\Model\AbstractModel $subject,
                                                  $result
       ) {
          $a=1;
   
           return $result;
       }
   
       /**
        * @param \Magento\Framework\Model\AbstractModel $subject
        * @return void
        */
       public function beforeAfterSave(
           \Magento\Framework\Model\AbstractModel $subject
       ) {
           $a=1;
       }
   
       public function beforeBeforeDelete(
           \Magento\Framework\Model\AbstractModel $subject
       ) {
           $a=1;
       }
   }

4. Execute bin/magento setup:upgrade.

5. Create/update a bundle product.

Expected result

The product is saved without errors.

Actual result

When saving the product, we get the error:
Could not save child: "Unknown entity type: Magento\Bundle\Model\Selection\Interceptor requested"

Additional information

No response

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @faradey. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce.

• For more details, review the Magento Contributor Assistant documentation.
• Add a comment to assign the issue: @magento I am working on this
• To learn more about issue processing workflow, refer to the Code Contributions.

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