The FBI is part of DOJ, which is an executive branch department under Biden's direct authority. If he thinks it's "simply wrong", he can just order them not to do it. He's not limited to "criticizing" it.
"Going forward, consistent with the President's direction, this Department of Justice – in a change to its longstanding practice – will not seek compulsory legal process in leak investigations to obtain source information from members of the news media doing their jobs," Justice Department spokesman Anthon Coley said in a statement Saturday.
That means they won’t subpoena journalists phone records when looking for whistleblowers. It doesn’t mean they won’t go after reader’s IP when looking for other suspects.