Excessive Application registration auto-approved emails to users not needing them

The resolution involved removing the API Manager "Manage Contracts" permission from the affected users. This action prevents them from approving API access requests, thereby stopping the auto-approval emails.

Here's the explanation in the doc link: https://docs.mulesoft.com/api-manager/latest/manage-client-apps-latest-task#task-prerequisite where it states

"To manually approve or reject requests, you must have:... The Organization Administrator, API Manager Environment Administrator, or the Manage Contracts permission" by removing the Manage Contracts permission the user won't have the ability to approve the API access requests hence no more auto approve emails.