I would not say this is a clear indication of a scam.

To understand why the account balance updated before the "spins took place" you need to understand how games are built and work.

There are two sides to every game:

1. The server side, this is where the game takes place using its RNG mechanism.
2. The client-side, the pretty picture running in the user's browser. This will "play" the outcome of the game as determined by the server mechanics.

So for a normal game, you will click a button, this action calls the server, the server runs the game, and returns the result to the UI. The UI then plays the outcome of the game (as a slot machine, crash game, scratch card... whatever).

By the time the game plays the UI to the user, the outcome has been determined. In some games, you will notice that your account balance goes up when the game loads.

In this case, I would assume that the game and its bonus spins are determined on the first call.

1. IsWin(1, 100) - user picked 5
2. runBonus(1, 100) - random number selected 52
3. creditWin()
4. returnDataToUI()
5. UI runs the data

Once the data is returned to the UI, the user plays the game not knowing that the result has already been determined.

There are other ways to write games like this and that would be to give the user "free spin credits". The code may look something like this:

1. IsWin(1, 100) - user picked 5
2. runBonus(1, 100) - random number selected 52
3. creditWin(), creditBonusCredits()
4. returnDataToUI()
5. UI runs the data

At this point, the user now has "bonus credits" which can be used to run a separate game...

In most cases an all in one game is preferred since managing credits etc. becomes a chore.