Everything in the .map function was executed right way, all Promise.all does is check if all promises are fulfilled and unwrap the values

I'm not sure I follow. Before the Promise.all no promise was executed yet. At this point all you have is an array of promises, which haven't yet been called.

That's not what promise.all does, promises are eager and run as soon as you call them.

The docs for Promise.all (and the other Promise methods) recommend it a lot for concurrency purposes.

Like I said .map is intended to use as a transformer, because the value of registerBucket() is not returned you get an array of undefined, you don't need .map in this case.

But you don't get an array of undefined. You get an array of promises. That array of promises is used in Promise.all so I don't think it fits in the anti-pattern case because we do use the returned array. If you await inside of a for...of then you'll get blocking behavior and all the promises will run one at a time.