In JIRA Server we notice that if a user sets the General Config setting "User email visibility" to Hidden, that is described as affecting only the Profile page:

Controls how users' email addresses are displayed in the user profile page.

But, the user email disappears from REST search requests, eg:

https://host.atlassian.net/rest/api/2/user?username=someuser

Ordinarily this would be ok, but in cloud, remote addons are dependant on information, and we require access to that information to work.

Workaround is to advise user to use the Masked option instead, but we feel Hidden should apply as documented to the Profile page, not the rest response, which is governed by the BROWSE_USERS permission in any case.