One important nuance: Santa Monica allows landlords to petition for an "individual rent adjustment" above the general increase if they can demonstrate increased operating costs (capital improvements, maintenance expenses, property tax increases). This requires a formal petition and hearing before the Rent Control Board.
If your landlord just sent you a notice of 8% increase without going through this process, it's likely invalid. Even if they did petition, you'd have the right to appear at the hearing and contest it. The Board rarely grants increases as high as 8%.
Also worth noting: Santa Monica has mandatory relocation assistance if the landlord tries to evict you for refusing an illegal rent increase. The amounts are substantial — $10K-$20K+ depending on unit size and tenant category.