Automatic capitalization of the username (email) in GCP IAM may occur due to the following reasons:
- The first letter of the username (email) is always capitalized.
- GCP IAM recognizes certain email providers like Gmail, Yahoo, etc., and automatically capitalizes the domain name part of the email address.
- Some web browsers automatically capitalize the first letter of the email address when it is entered. This can be disabled or changed in the browser settings.