New source found from dndbeyond.com

ddb_main/node_modules/@mui/material/Backdrop/Backdrop.js

@@ -8,7 +8,7 @@ import PropTypes from 'prop-types';
 import clsx from 'clsx';
 import composeClasses from '@mui/utils/composeClasses';
 import styled from '../styles/styled';
-import useThemeProps from '../styles/useThemeProps';
+import { useDefaultProps } from '../DefaultPropsProvider';
 import Fade from '../Fade';
 import { getBackdropUtilityClass } from './backdropClasses';
 import { jsx as _jsx } from "react/jsx-runtime";
@@ -49,7 +49,7 @@ const BackdropRoot = styled('div', {
 }));
 const Backdrop = /*#__PURE__*/React.forwardRef(function Backdrop(inProps, ref) {
   var _slotProps$root, _ref, _slots$root;
-  const props = useThemeProps({
+  const props = useDefaultProps({
     props: inProps,
     name: 'MuiBackdrop'
   });