Bug: support fetchPriority in camel-case on DOM nodes.

[fmacherey]

At the moment, the HTML fetchPriority is only supported written as fetchpriority, see #26810

But as per DefinitelyTyped/DefinitelyTyped#65972 it is required in @types/react to be written as fetchPriority as it is also for other props e.g. imageSrcSet.

With spelling it as camel-case, react ejects a warning:

Warning: React does not recognize the `fetchPriority` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `fetchpriority` instead. If you accidentally passed it from a parent component, remove it from the DOM element.
    at link
    at head
    at Head (webpack-internal:///./node_modules/next/dist/pages/_document.js:258:1)
    at html
    at Html (webpack-internal:///./node_modules/next/dist/pages/_document.js:680:119)
    at MyDocument (webpack-internal:///./pages/_document.tsx:24:1)

Relevant versions:

"@types/react": "^18.2.20",
"react": "^18.2.0",
"react-dom": "^18.2.0",
"next": "13.4.12",
"typescript": "^5.1.6", 

Steps To Reproduce

Example component:

import React from "react";
import NextHead from "next/head";

type Props = {
    webP: string;
};

export const ImagePreload: React.FC<Props> = React.memo(({ webP }) => (
    <NextHead>
        <link
            key={`image-preload-${webP}`}
            rel="preload"
            as="image"
            imageSrcSet={webP}
            fetchPriority="high"
        />
    </NextHead>
));
ImagePreload.displayName = "ImagePreload";

[Daniel3711997]

Still an issue...

[eps1lon]

Fixed in #25927 which is part of the Canary and Experimental release channel.

Types were already added.

[kostia1st]

Is the fix planned for React 18.x.x?

[eps1lon]

No. It will be part of React 19 and is already available in the React 19 RC (19.0.0-rc.0)