Every contract has that, either party can exit the contract under normal conditions. You can cancel your Netflix subscription with a short notice period. They can do the same. They use the notice period as grace period for you to accept the new conditions. You accept a new contract with new conditions.

I negotiated my mobile phone or internet contracts again and again, to get better deals. I threaten to leave, they throw a bone. Because they know I have options. Providers who know you don’t will squeeze you however they please.