Hey there,
Usually, dev versions contain important bug fixes and new features, however, they also may come out with some missed bugs and issues although we test them before releasing. Keeping the stable version allows avoiding this as a stable version gathers the same features and fixes as the preceding dev version thoroughly tested by us and our users.
We released the dev v2.21.2 update with the fix for the AR ratio issue that occurred on the v2.21.1 dev version. You can check this thread for more detail.