Structural Typing vs Excess Property Check https://talohana.com/blog/typescript-excess-property-checks

test.ts

type Data = {
    id: string;
};

const data: Data = {
    id: "123",
    name: "Hello!",
}

const data2  = {
    id: "123",
    name: "Hello!",
};

const data3: Data = data2;

type Func = () => {
    id: string;
};

const func1 = (): Data => {
    return {
        id: "123",
        // No error on an excess property!
        name: "Hello!",
    };
};

const func2: Func = () => {
    return {
        id: "123",
        // No error on an excess property!
        name: "Hello!",
    };
};