This recent possibility is more of the same. If Flynn had a secret deal with Mueller, then that could be a problem for Flynn. Whenever a defendant in federal court pleads guilty under a Plea Agreement, the Court asks a series of questions to be sure the plea is knowing and voluntary. One question asked is whether there are other promises made that are not reflected in the Plea Agreement. If that question was asked and Flynn said No, then either he lied at the time, or he is lying now. Neither outcome will be good for Flynn.
Flynn doesn’t have a problem. The prosecutor has a huge problem. Intimidating and threatening a witness, and Flynn is a witness in his own case, are felonies; as is suborning perjury. It’s also obstruction of justice.
Because Flynn was threatened if he didn’t agree to what the prosecutor wanted, he has an absolute defense.