React uses keys to help with Reconciliation (i.e. how it calculates the DOM diff for each render).
As noted in ‘What should I use for a key?’ Be careful what you use for a key. Using an array index isn’t a best practice… aim to use a unique id.
Why can’t i put key in default props (or define the default somewhere else)?
What should I use for a key?
What are some examples where I should manually change a key?
Do keys across an app all need to be unique?
No - Keys used only need to be unique among their siblings.