Being kept in the dark doesn’t erase rights
Landlords should not rent out unpermitted units, and renting one to you while hiding its illegal status raises real concerns. While the exact disclosure duties can depend on the situation, a landlord collecting rent for an unlawful home cannot fairly turn around and use that illegality against you.
In practice, many tenants only discover a unit is illegal after they move in — when problems arise, the city gets involved, or the landlord suddenly claims the unit "isn't legal." A landlord who knowingly rented an unpermitted unit, took your money, and concealed the problem may face consequences, and you may have claims relating to the situation.
What matters most is that being kept in the dark does not erase your rights. You generally still have habitability protections, eviction-process protections, and deposit rights, and possibly claims tied to the unit's illegal status.
If you learned after moving in that your unit is unpermitted and feel misled, that is worth examining. A free, confidential review can look at what you were told and help you understand your options.
This is general information about California tenant rights, not legal advice. Every situation is different.