$group output in a stable order
What changes in $group output in a stable order compared with MongoDB and what your application has to do.
This difference is of the Stronger guarantee kind.
What MongoDB does
The output of $group changes order from one run to the next with the same data.
What TeselaDB does
It always comes out in the same order for the same data.
What your application has to do
Nothing. If you need a specific order, add $sort.