Allowing the deletion of protected branches by users with push access increases the risk of accidental or intentional branch removal, potentially resulting in significant data loss or disruption to the development process.

Deny the ability to delete protected branches to ensure the preservation of critical branch data. This prevents accidental or malicious deletions and helps maintain the integrity and stability of the repository.

• https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-protected-branches/about-protected-branches#allow-deletions