That used to be true. When they rolled out the Silence system it started at 24 hours then doubled each time.
Last year, they changed the penalties because Silence alone was not curbing the unwanted behavior. They changed the first offense to a week Silence and future penalties are Suspensions, up to Account Closure.
While there are automated warnings that you might get, they are not a guarentee. The “warning” is the EULA and policies we agree to. Technically. So just keep that in mind.
If you appealed via ticket, then that is all you can really do.
As for penalizing false reporters. Players are encouraged to report behavior they think violates the rules. If they are not correct, then the GM won’t apply a penalty. However, coordinated mass flagging to disrupt the game and target someone can get those players suspended. Blizz does not like abuse of the reporting system. That can be hard to prove though unless they do it on a stream or something.