When you finish a hand of Belote and you do not want to play another round, please always be sure to properly quit the game and fully exit the game table.
To do this, you need to tap the House Button at the bottom left side of your screen, just above your profile picture. Then tap "Leave the table".
All the other ways of leaving the game (app closure for example) do not guarantee a complete exit from the game and can cause a loss of Chips.