Landlord Asking For Full Year Of Rent Upfront (california)

(I'm in California)
My brother is a college student renting an apartment on a fixed one-year lease and he is being asked to pay $10,000 upfront for rent for the entire lease, plus a security deposit. He's subletting from a previous tenant/the other residents who are on the original lease, so it's not the property owner's policy, but his future roommates'. His future roommates want him to put this money into an account that the rent will be automatically paid out from monthly. He would meet all income requirements with my parents as cosigners, which I assume the rest of his roommates also needed to secure the original lease as they're all college students.
Is this legal? Are the laws different because it's his roommates, and not the property owner? I've never heard of this kind of thing before. Thank you in advance for any help!
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