MUI theming no longer working

[chrishj59]

Checklist

• [ x] This is not covered in the repository examples.
• I am using the package latest version.
• [ x] This is a bug report or an enhancement proposal.

Description

I have migrated MUI to V5 using Nextjs 12.0.3

It is not possible to use V2 as this results ' expected export' error so I am using 1.29.0

Write here your issue description.
The theme styling no longer works
`MUIRichTextEditor: {
styleOverrides: {
root: {
marginTop: 20,
marginBottom: 100,
},
editor: {
borderBottom: '1px solid gray',
height: '10rem',
maxHeight: '8rem',
overflow: 'auto',

				},
			},
		},`

[chrishj59]

Since the PR #292 was created I am able create the styling using using the new MUI styling structure.
MUIRichTextEditor: { styleOverrides: { root: { marginTop: 20, marginBottom: 20, }, editor: { borderBottom: '1px solid gray', height: '10rem', maxHeight: '8rem', overflow: 'auto', // minHeight: '8rem', }, }, },