I don't know if any of you have noticed what happens to me with slots. With some providers, as you can see in the image below, I can see the difference between the money I had when I started betting, in red at the top, and how my session is going, in red at the bottom.
I have experienced this on different casinos too. The inconsistency between the game balance (according to the game provider) and the main account balance (according to the casino) is usually due to synchronization issues
(it doesn’t get updated in real time). When the game session ends, normally, your main account will reflect your actual ad correct balance.
Some casinos will just hide your main account balance and instead show it as "in play, or something like that, during the game session to avoid such confusion.