What happens during a custom setting deployment step regarding environment variable values?

During a custom setting deployment step, environment variable values undergo a process where they are searched and matched with the corresponding values in the target environment. This ensures that any configurations or settings that were tailored for a particular environment can be appropriately linked to those in the new environment. The matching process is critical for maintaining the integrity and functionality of the application across different stages of deployment.

This option highlights the mechanism that enables developers and deployment engineers to ensure proper functioning of custom settings after migration, as it helps in resolving any discrepancies between the source and target environments. Properly matched environment variable values contribute to smoother transitions and reduced errors during the deployment process.

In contrast, the other options do not accurately represent what occurs during this step. Keeping values constant, logging values, or deleting them does not capture the essence of the search and match process that is vital for ensuring that the deployed application behaves as intended in the new environment.