There is no way to control the order of these tabs. Sometimes, when creating a new Database, the order changes. When creating a Space that consists of more than a few Databases, this is inconvenient and can be frustrating.
Is it possible to give control of the order of these Database tabs to the user?
Just worth pointing out that there is a certain logic to the ordering, namely that parent databases precede any linked child databases. This is why the ordering may change (as relations are added).
Also, this view is intended to be for admins/creators rather than regular users. If everyday users are finding it confusing, perhaps you could change permission levels, so that they do not have admin/creator access, and instead provide specific views of the data (table view, board view, list view etc.) that are simplified in what they show.