Please update the  documentation for the rest/api/latest/user/search to include examples on how to search for users and portal only customer using the email address since all the examples are still using the username that is going to be deprecated soon.

Not even the REST API migration guide and deprecation notice - removal of username and userkey is having clear examples showing that this can be achieved by using e.g. below Request:

• https://HOSTNAME/rest/api/latest/user/search?query=something@example.com

The above REST API call will return, among the other things, the accountId for the user (or portal only customer) having the given email address (in this case: something@example.com)