What kind of checks and warnings does React.StrictMode activate?

Question

From React documentation on React.StrictMode and React.Fragment:
Both Fragment, StrictMode does not render any visible UI. It activates additional checks and warnings for its descendants.

Question: What kind of checks and warnings does React.StrictMode activate on this code?

import React from 'react'

export default function About() {
    return (
        <React.StrictMode>
            <h1>About page</h1>
            <p>This is a text deescribing the About page</hp>
        </React.StrictMode>
    )
}

Answer 1

The article you linked states exactly what it helps with:

StrictMode currently helps with:

• Identifying components with unsafe lifecycles
• Warning about legacy string ref API usage
• Warning about deprecated findDOMNode usage
• Detecting unexpected side effects
• Detecting legacy context API