Buying non permitted property

[Amber Straub]

I am purchasing my second house hack! I have found a property where the main home is currently being rented and the previous owner has converted the shed (permitted as a shed) into a 2 bedroom one bath home/ADU. The ADU looks great but the problem is that is has not been permitted by the city. I am getting mixed signals about how important that is and/or what type of issues or concerns I should have about it. I plan on keeping as a rental but doing a refinance in the future. Coming here looking for any experienced advice on this dilemma. Thanks!