Why does my primary email change switch with my secondary email address when I log in with SSO?
Zendesk considers all information passed-in via the SSO response to be the truth, and will update a user's profile accordingly. This means if a user is logging in with a secondary email address associated with their user profile AND the SSO response is sending in an external ID, Zendesk will change the order of email addresses on the user profile to have the email currently being used to login as the primary email address.
For example, if you have two Gmail accounts that you've added as primary and secondary email addresses for your Support user, and if you log into your Support account via Google SSO with your secondary email address Gmail account, then the primary email address on your Support user profile will switch with your secondary email.
Since this behavior is hard coded, if you would not want this to happen, please ensure that from here on out, you only log into your Support account with the email address (or account you log in via SSO) you'd like set as the primary email on your user profile.