An example of incorrect usage of props to set state in ctor. When component rerenders the ctor will not be run again and any mutations to props will not be reflected in current state.

PropsSetToStateInCtor.tsx

import React, { useState, useEffect } from "react";
import "./App.css";

const App: React.FC = () => {
  const [user, setUser] = useState({ name: "john", email: "[email protected]" });

  useEffect(() => {
    setTimeout(() => {
      setUser({ name: "jane", email: "[email protected]" });
    }, 500);
  }, []);

  return <TestComponent user={user} />;
};

interface IUser {
  name: string;
  email: string;
}
interface IProps {
  readonly user: IUser;
}

interface IState {
  readonly userName: string;
}

class TestComponent extends React.Component<IProps, IState> {
  constructor(props: IProps) {
    super(props);

    this.state = {
      userName: props.user.name
    };
  }

  public render(): React.ReactElement {
    return <div>{this.state.userName}</div>;
  }
}
export default App;