https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-key.md

Let's enable the new option checkFragmentShorthand in standard:

    "react/jsx-key": ["error", {
      "checkFragmentShorthand": true,
    }],

Warn if an element that likely requires a key prop--namely, one present in an
array literal or an arrow function expression.

Rule Options

...
"react/jsx-key": [<enabled>, { "checkFragmentShorthand": <boolean> }]
...

checkFragmentShorthand (default: false)

When true the rule will check if usage of the [shorthand fragment syntax][short_syntax] requires a key. This option was added to avoid a breaking change and will be the default in the next major version.

Examples of incorrect code for this rule:

[<></>, <></>, <></>];

data.map(x => <>{x}</>);