It's not lying if ChatGPT is correct (which it often is), so repeating ChatGPT isn't lying (since ChatGPT isn't always wrong); instead the behaviour is negligent or in the case of a lawyer grossly negligent since a lawyer should know better to check if it is correct before repeating it.
As always mens rea is a very important part of criminal law. Also, just because you don't like what someone says / writes doesn't mean it is a crime (even if it is factually incorrect).