If you add a key prop to CToast (e.g. mapping a list of toasts) this warning will show in the console:
key is not a prop. Trying to access it will result in undefined being returned.

As you can see CToast attempts to read and forward the key prop. This should be a differently named prop instead.

It's also not typed correctly. keys are numbers or strings

See docs
https://react.dev/warnings/special-props