Cashback means a percentage of your net losses for the week — total losses minus total winnings — is returned to your account. This is not a bonus; it applies directly based on your net losses.
Each week is calculated separately. If your winnings exceed your losses in a given week, no cashback applies for that week. Cashback is only calculated when there is a net loss, at the rate for your tier.
Net losses from slots, live casino, and cricket betting are all combined to calculate cashback. Spending regular time on slot games means you will feel the benefit of cashback more.