Landlord Is Enforcing A $40 Overnight Guest Fee And A 7 Pm Guest Cutoff

Location: Berkeley, CA

Edit: Originally posted in r/Renters and was directed to post here for most accurate information.

I moved into a shared house in Berkeley in 2026 and signed an individual lease. I share the house with two other roommates. My landlord and his wife live part-time in a separate ADU in the backyard and occasionally use the shared living room and kitchen.

My girlfriend occasionally visits and recently stayed overnight. My landlord sent me a message stating that, under our agreement, guests are allowed only during the daytime and must leave by 7 PM. He also said that overnight guests must be announced in advance, approved by him, and are subject to a $40 charge per night.

The lease contains a provision referring to a $40 overnight guest fee, but it does not specify that guests must leave by a certain time.

My girlfriend is an occasional guest, and we are respectful of my roommates and clean up after ourselves. She is not living here in any way.

I am trying to understand:

1. Is a $40 per night guest charge enforceable in Berkeley as it appears in the lease? I have been reading conditional legislature that changes tenant protections if the landlord lives in an ADU, but I do not know how to interpret it for this situation.
2. Can my landlord impose or enforce a time guest cutoff if that restriction is not clearly stated in the signed lease?
3. Does this implicate my right to quiet enjoyment or any California/Berkeley tenant protection laws?
4. How should I respond to my landlord, and what should I document or avoid doing?

I can provide the exact lease language if helpful. I want to understand whether my landlord can charge for occasional guests in this way and want to be reasonable.