Presidents have a right to expect a certain amount of privacy. If someone is going to listen to a call a President makes, or listen to reports about what he said from others, and then decides to release that information to the public, the identification of the individual also should be made public. To conceal the identity of the ‘whistle blower’ and to use the information released to attack the President is a kind of Klu Klux Klan/Antifah faceless masked subversion of the right of a person attacked to face their accuser (s).
Whoever made a secret squealer/rat provision to hide the identity of those that disclose Presidential phone call content without authorization to anyone not designated to receive the information was making a way to exploit Presidential content for political purposes, and that was wrong.
There is no reason to conceal the identity of the informant unless there is a legal reason that conveyed the right. If there is such a provision then the whistle blower should not hide behind a sheet and should step forward and claim responsibility for his or her act that was made by the Democrats the centerpiece of their impeachment efforts.