Hovering over icons in toolbar generates a warning

[w3bdesign]

Expected Behavior

I expect no warnings to display.

Current Behavior

When hovering over icons in the toolbar I get the following warning in my console.

Warning: findDOMNode is deprecated in StrictMode. findDOMNode was passed an instance of Transition which is inside StrictMode. Instead, add a ref directly to the element you want to reference. Learn more about using refs safely here: https://fb.me/react-strict-mode-find-node

Steps to Reproduce (for bugs)

1. Install React with CRA and --template=typescript with @material-ui/core
2. Install @types/material-ui and @types/mui-datatables
3. Implement the simple example from the docs
4. Start the application and hover over an icon in the toolbar
5. See console

See screenshot below:

Your Environment

"dependencies": {
"@material-ui/core": "^4.11.0",
"@material-ui/icons": "^4.9.1",
"@testing-library/jest-dom": "^5.11.2",
"@testing-library/react": "^10.4.7",
"@testing-library/user-event": "^12.1.0",
"@types/jest": "^26.0.8",
"@types/material-ui": "^0.21.7",
"@types/mui-datatables": "^3.1.1",
"@types/node": "^14.0.27",
"@types/react": "^16.9.44",
"@types/react-dom": "^16.9.8",
"@types/react-router-dom": "^5.1.5",
"easy-peasy": "^3.3.1",
"mui-datatables": "^3.3.1",
"react": "^16.13.1",
"react-dom": "^16.13.1",
"react-scripts": "3.4.1",
"typescript": "^3.9.7"
},
"devDependencies": {
"@typescript-eslint/eslint-plugin": "^3.8.0",
"@typescript-eslint/parser": "^3.8.0",
"eslint": "6.8.0",
"eslint-config-airbnb": "^18.2.0",
"eslint-config-airbnb-typescript": "^9.0.0",
"eslint-config-prettier": "^6.11.0",
"eslint-plugin-import": "^2.22.0",
"eslint-plugin-jsx-a11y": "^6.3.1",
"eslint-plugin-prettier": "^3.1.4",
"eslint-plugin-react": "^7.20.5",
"eslint-plugin-react-hooks": "^4.0.8",
"prettier": "^2.0.5"
}

[patorjk]

These warnings are from Material UI itself. This library (as of version 3.2.0) no longer uses findDOMNode.