Lawyers' professional ethics should not reveal the secrets of their clients, and they are not obliged to report the learned criminal facts when handling entrusted matters, otherwise it will violate professional ethics. People hired you, but you took the money and sold them. In addition, encouraging informers is a secret service and an act of the police state.
However, if lawyers are informed of major criminal cases, such as terrorist attacks, they are obliged to report these cases. This is the rule after weighing the pros and cons.