Not necessarily, but the possibility exists. I haven't had the pleasure of seeing how mueller got the evidence he used against flynn, but if it is tainted then flynn walks. Sadly so to will manafort, who really is a scumbag.
Please take a legal course. Something that explains how the criminal justice system works, because you are more clueless than Alicia Silverstone.
Flynn pleaded guilty, and gave a full allocution to the judge. And both Flynn and his lawyer signed the agreement where they would not appeal the guilty finding.
Allocution - Wikipedia
An
allocution, or
allocutus, is a formal statement made to the court by the defendant who has been found guilty prior to being sentenced. It is part of the criminal procedure in some jurisdictions using
common law.
In
plea bargains, an allocution may be required of the defendant. The defendant explicitly admits specifically and in detail the actions and their reasons in exchange for a reduced sentence.
In principle,
that removes any doubt as to the exact nature of the defendant's guilt in the matter.