Best practices for avoiding downtime when making changes to the API? (Vercel)

I am making a React-Django application which I have deployed using Vercel.

My concern is that sometimes I will need to make changes to the API and I am not sure how to handle that without causing downtime in production.

Say for example that I change an endpoint's payload (for example, I might change the variable names or its structure). Say I reflect those changes in the frontend, making sure that the frontend can accept the new payload.

Now, if I push the new API to live and the front-end has not been pushed to live yet, the (old) front-end will make get a payload it won't be able to work with and thus the app will crash. If on the other hand I push the new front-end to live but the new API is not live yet, the (new) front-end will get the old payload's structure which it's no longer able to work with. The app will crash in this case too.

How can I ensure that when I make changes to the API and to the frontend I can do so whilst also avoiding any downtime? What are the best practices to do this?

Any help is appreciated, thank you!