When I fill in the appropriate modules that you're using, this code here works just fine for me in node v16.13.2:

const request = require('request');
const { v4: uuidv4 } = require('uuid');
const fs = require('fs');

let imageInit = 'https://via.placeholder.com/350x150';
let image = imageInit.replace('350x250', '200x200');
if (!image) {
    return;
}

var download = function(uri, filename, callback) {
    request.head(uri, function(err, res, body) {
        console.log('content-type:', res.headers['content-type']);
        console.log('content-length:', res.headers['content-length']);

        request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
    });
};

const generatedName = uuidv4();
const finalName = generatedName.concat('.png');
console.log(finalName);

download(image, finalName, function() {
    console.log('done');
});

Is there something different in your whole code? Or does this specific code not work for you?

Things you can examine in your own code:

1. Add error handling to both request() stream and to the writeStream to log any errors.
2. Try to load the https://via.placeholder.com/200x200 URL into your own browser to just see if that works.
3. Tell us more about "doesn't work anymore" actually means. What do you observe? What do you see in the logs? Where does it stop executing?

Here's a version of the code with a lot more error handling/logging:

const request = require('request');
const { v4: uuidv4 } = require('uuid');
const fs = require('fs');

let imageInit = 'https://via.placeholder.com/350x150';
let image = imageInit.replace('350x250', '200x200');
if (!image) {
    return;
}

var download = function(uri, filename, callback) {
    request.head(uri, function(err, res, body) {
        if (err) {
            console.log(err);
            callback(err);
            return;
        }
        console.log('content-type:', res.headers['content-type']);
        console.log('content-length:', res.headers['content-length']);

        let wStream = fs.createWriteStream(filename).on('error', err => { console.log(err); });
        let rStream = request(uri).on('error', err => { console.log(err); });
        rStream.pipe(wStream).on('close', () => callback(null));
    });
};

const generatedName = uuidv4();
const finalName = generatedName.concat('.png');
console.log(finalName);

download(image, finalName, function(err) {
    if (err) {
        console.log('finished with error');
    } else {
        console.log('done');
    }
});

Please note that the request() module has been deprecated so really shouldn't be used in new code going forward. A good set of alternatives here.

After a lot of research I found the source of the problem; I had process.exit(1); in the end of my code.

This was added in order to end the execution of the whole code once everything is finished, but apparently with this the image is not downloaded too. Removing it fixed the issue in addition of the snippet provided by @jfriend00.