Override Material UI 5 Button Text in my theme

I'm trying to change the MuiButton text to lowercase but I can't find a way.
I share code and screenshot.

theme.jsx

import { createTheme, } from "@mui/material/styles";

export const theme = createTheme({
  palette: {
    mode: "light",
    primary: {
      main: "#E9531E",
    },
    secondary: {
      main: "#4357AD",
    },
  },
  typography: {
    fontFamily: "Roboto",
    textTransform: "none",
  },...

overrides: {
    MuiButton: {
      root: {
        background: "linear-gradient(45deg, #FE6B8B 30%, #FF8E53 90%)",
        border: 0,
        borderRadius: 3,
        boxShadow: "0 3px 5px 2px rgba(255, 105, 135, .3)",
        color: "white",
        height: 48,
        padding: "0 30px",
        textTransform: "none",
      },
    },

App.jsx

import Navbar from "./components/Navbar";
import Login from "./pages/Login";

function App() {
  return (
    <div className="App">
      <Navbar />
      <Login />
    </div>
  );
}

export default App;

index.jsx

import React from "react";
import ReactDOM from "react-dom/client";
import "./index.css";
import App from "./App";
import { ThemeProvider } from "@mui/material";
import { theme } from "./theme";

const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(
  
  <ThemeProvider theme={theme}>
    
    <App />
    
  </ThemeProvider>
);

The global text style changes but the button style does not.

I have tried styled but I don't know how to use them well.

You need to change the style overrides to this:

const theme = createTheme({
  ...,
  components: {
    MuiButton: {
      styleOverrides: {
        root: {
          background: "linear-gradient(45deg, #FE6B8B 30%, #FF8E53 90%)",
          border: 0,
          borderRadius: 3,
          boxShadow: "0 3px 5px 2px rgba(255, 105, 135, .3)",
          color: "white",
          height: 48,
          padding: "0 30px",
          textTransform: "none",
        },
      },
    },
  },
});

Check out the docs for more information:
https://mui.com/material-ui/customization/theme-components/#theme-style-overrides