Before to star that, I want to show you this when I put .toArray() at the end of the aggregate on MONGOSH:
[
{
subs: [
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object],
[Object], [Object], [Object], [Object]
]
}
]
why the return is like a matrix of 4x12 dimension?