At some point it becomes a failure to deliver goods and warrants a credit card chargeback. If you bought a 10-piece kitchen set on Amazon and only 3 pieces arrived, you’d want a refund.
This is because of the terms of service you agree to when you first signed up to OpenAI, which has "WE DO NOT WARRANT THAT THE SERVICES WILL BE UNINTERRUPTED, ACCURATE OR ERROR FREE" in it, in the "Disclaimer of Warranties" section. https://openai.com/policies/terms-of-use
They upfront tell you that it won't be uninterrupted, so I'm guessing you have little legal rights here for some hours of downtime each month. If it was unavailable for a month or more, things would obviously change.