Is the deal fair?

Yes, and you do not have to take our word for it. Every online match publishes a SHA-256 fingerprint of its shuffle before the first card is dealt, and reveals the number behind it when the match ends. Re-running the shuffle with that number must reproduce the exact deal that was played — which a server that reshuffled midway could not arrange.

The rules engine only ever reads the hand of the player whose turn it is, and each player is sent a view of the game with every other hand removed from the data entirely.