Always I am getting 401 error when I want to send mail through graph API, while it is generating token successfully

This is my node js code as below

import axios from 'axios';
import { ConfidentialClientApplication, LogLevel } from '@azure/msal-node';

// Static configuration per your request
const clientId = '****';
const clientSecret = '*******';
const tenantId = process.env.AZURE_TENANT_ID || '*******';
const senderUpn = '******@gmail.com';
const toAddress = '******@gmail.com';

const cca = new ConfidentialClientApplication({
    auth: {
        clientId,
        clientSecret,
        authority: `https://login.microsoftonline.com/${tenantId}`,
    },
    system: {
        loggerOptions: {
            loggerCallback: () => {},
            logLevel: LogLevel.Error,
            piiLoggingEnabled: false,
        },
    },
});

async function acquireAppToken() {
    const scopes = ['https://graph.microsoft.com/.default'];
    const result = await cca.acquireTokenByClientCredential({ scopes });
    return result.accessToken;
}

function buildMessage() {
    return {
        message: {
            subject: 'First Mail From Postman',
            body: {
                contentType: 'Text',
                content: 'The new cafeteria is open.',
            },
            toRecipients: [
                { emailAddress: { address: toAddress } },
            ],
            ccRecipients: [
                { emailAddress: { address: toAddress } },
            ],
        },
        saveToSentItems: true,
    };
}

async function sendMailOnce() {
    try {
        const token = await acquireAppToken();
        console.log('Access token (app-only JWT):', token);
        const url = `https://graph.microsoft.com/v1.0/users/${encodeURIComponent(senderUpn)}/sendMail`;
        const payload = buildMessage();
        const res = await axios.post(url, payload, {
            headers: { Authorization: `Bearer ${token}`, 'Content-Type': 'application/json' },
            validateStatus: () => true,
        });
        if (res.status === 202) {
            console.log('Mail accepted for delivery.');
        } else {
            console.error('Failed to send mail:', res.status, res.statusText, res.data);
            process.exitCode = 1;
        }
    } catch (e) {
        console.error('Error acquiring token or sending mail:', e);
        process.exit(1);
    }
}

sendMailOnce();

When I am running the page its response is coming as like below

Access token (app-only JWT): ********

Failed to send mail: 401 Unauthorized

Always I am getting 401 unauthorized error

I have the app permission as like below

Requesting the communities help for identification of issue and resolution