Switching jobs? I mea yea you could but again that's not exactly an option for a lot of people. Particularly in the short term.
Mean while your app is stuck on a loading screen with an infinite spinner and bad reviews are flowing into the app store.
Sure - your program can degrade gracefully. But that should be for informational / diagnostic purposes only. It doesn't change the fact that you're using a system that is not living up to its data contract.
At some point, the most efficient way to push back against bad code is by validating the contract at the boundary. Then, when that breaks, you have a lot more leverage to go around and demand fixing things.
Or, better yet, use systems that don't allow contracts to be so easily broken. Static typing is an example of that.
If there is some legacy reason something cannot be fixed and has to keep returning bad data, then yes, there is 100% a reason to have two endpoints that do the same thing... usually prefixed with /v2/ or something