in ExtReact 6.6.2 it is not possible to use a Button component inside a plain HTML Component:

HTML Code:
import React from 'react';
import { Container, Button } from '@sencha/ext-modern';

export default function About() {
  return (
    <Container padding="20">
      <h1>About this App</h1>
      <p>Lorem ipsum dolor sit amet.</p>
            <Button text="test" />

The error is:

PHP Code:
Warning: <Button /> is using incorrect casing. Use PascalCase for React components, or lowercase for HTML elements.    in Button (created by About)    
in div 
It was possible before 6.6.2 and it would be a really expensive change for me to rewrite my complete code.

Can someone help?