Sovereign Immunity means you cannot sue the state itself. It does not apply to an employee or official of the state who is doing something not authorized by state law. Presumably no law authorizes the state to embezzle, or to commit fraud. So if someone does that, even acting with purported governmental authority, that person is simply a criminal who is also a corrupt state employee or official. No Sovereign Immunity applies.
In a Civil Rights case with merit, either someone acting in the name of the state has violated the law, or the law itself was unconstitutional, so in either case the action was ultimately not lawful, and again Sovereign Immunity does not apply.
Sovereign Immunity does not block suits in which it is claimed that governmental action, state or federal, violates law or (n the US) the Federal Constitution (or a state constitution). Such suit may win or lose, but it can be brought.
I don't see how Sovereign Immunity could apply to an UPL case. A government makes law, but it does not practice law.