这是您的错误的错误信息

auth/invalid-email：The provided value for the email user property is invalid. It must be a string email address.

检查以确保您的onSubmitHandler在您的formData状态范围内，因为您的email和password可能未定义。

您的代码有2个问题，1：检查电子邮件和密码字段中onChange的拼写。2：将defaultValue更改为value
下面是工作代码：

import React, { useState } from 'react';
import { Link, useNavigate } from 'react-router-dom';
import { BsFillEyeFill } from 'react-icons/bs';
import {
  getAuth,
  createUserWithEmailAndPassword,
  updateProfile,
} from 'firebase/auth';

const Signup = () => {
  const [showPassword, setShowPassword] = useState(false);

  const [formData, setFormData] = useState({
    email: '',
    name: '',
    password: '',
  });

  const { name, email, password } = formData;
  const navigate = useNavigate();

  const onChange = (e: any) => {
    setFormData((prevState) => ({
      ...prevState,
      [e.target.id]: e.target.value,
    }));
  };

  const onSubmitHandler = async (e) => {
    e.preventDefault();
    console.log('email is ', email, password);
    try {
      const auth = getAuth();
      const userCredential = await createUserWithEmailAndPassword(
        auth,
        email,
        password,
      );
      const user = userCredential.user;
      alert('Signup Success');
    } catch (error) {
      console.log(error);
    }
  };

  return (
    <div className="d-flex align-items-center justify-content-center w-100 mt-5 mb-5">
      <form
        className="bg-light p-4 rounded-3 border border-dark border-3"
        onSubmit={onSubmitHandler}
      >
        <h4 className="bg-dark p-2 mt-2 text-light rounded-2 text-center">
          Sign Up
        </h4>
        <div className="mb-3">
          <label htmlFor="exampleInputEmail1" className="form-label">
            Enter Name
          </label>
          <input
            type="text"
            value={name}
            id="name"
            onChange={onChange}
            className="form-control"
            aria-describedby="nameHelp"
          />
        </div>

        <div className="mb-3">
          <label htmlFor="exampleInputEmail1" className="form-label">
            Email address
          </label>
          <input
            type="email"
            value={email}
            onChange={onChange}
            className="form-control"
            id="email"
            aria-describedby="emailHelp"
          />
          <div id="emailHelp" className="form-text">
            We'll never share your email with anyone else.
          </div>
        </div>

        <div className="mb-3">
          <label htmlFor="exampleInputPassword1" className="form-label">
            Password
          </label>
          <input
            type={showPassword ? 'text' : 'password'}
            value={password}
            onChange={onChange}
            className="form-control"
            id="password"
          />
          <span>
            Show Password{' '}
            <BsFillEyeFill
              className="text-primary ms-2"
              style={{ cursor: 'pointer' }}
              onClick={() => setShowPassword((prevState) => !prevState)}
            />
          </span>
        </div>

        <button type="submit" className="btn btn-primary">
          Sign Up
        </button>

        <div>
          <h6>Login with Google</h6>
          <span>Already User?</span> <Link to="/signin">Login</Link>
        </div>
      </form>
    </div>
  );
};

export default Signup;

const auth = getAuth();

我认为这行代码是错误的。你想用getAuth进行身份验证，但身份验证是什么？
必须将app传递给getAuth(app)