I changed my email address on the forum.
I cannot log in with my new email address, but I can still log in with my old email address. Is email change broken?
The Gradle Forums does not have its own user accounts. You can login with GitHub or a Gradle Plugin Portal account. The email address that can be changed in the forums is used for forum notifications.
The Gradle Plugin Portal account can be managed at plugins.gradle.org, but due to a security concern self-service email changes are not currently allowed and require a direct request with the Gradle team.
Specifics around what to do for the email change case were just added to the repository used for Plugin Portal requests: GitHub - gradle/plugin-portal-requests: Gradle Plugin Portal issues and requests.