When upgrading from Entity Framework core 6 to EF core 7, I had errors when trying to update related entities

The problem is detailed in a stackoverflow thread : https://stackoverflow.com/questions/74896336/replace-multi-level-relationship-in-entity-framework-core-6-vs-7

This is a minimal reproducible example to better illustrate the problem. An image of the ERD model of the tables is inside the project (DB_ERD_Model.png)

• Create a DB
• Execute the sql script entityFrameworkMigration.sql inside the project to create the tables
• Run the tests inside ParentServiceRepositoryTest. They will succeed
  • The project is configured to use EF core 6
  • Connection string is inside the ParentServiceRepositoryTest constructor
• Upgrade to EF core 7 :
  • Upgrade the following packages from 6.0.13 to 7.0.2 :
    • Microsoft.EntityFrameworkCore
    • Microsoft.EntityFrameworkCore.Tools
  • Upgrade the following packages from 6.0.8 to 7.0.1 :
    • Npgsql.EntityFrameworkCore.PostgreSQL
• Run the tests inside ParentServiceRepositoryTest another time. They will fail

The project contains the following structure :

• Inside the EntityFrameworkMigration project
  • Inside the Models folder, there is the DB models and the DB context test_localContext
  • ParentServiceRepository that contains the method UpdateParentChild that makes the update. This method is tested in ParentServiceRepositoryTest
• Inside the EntityFrameworkMigrationTest project
  • ParentServiceRepositoryTest contains the tests for UpdateParentChild method