When paying with assets like MATIC or tokens that are not a stablecoin, you may receive a small refund back into your wallet after you’ve paid a bill. When we swap tokens for fiat currency we get a quote for the trade using the maximum amount that the trade may require. If the actual trade requires less than the maximum amount, we’ll return the unused tokens back into your wallet. This works similarly to swapping on a decentralized exchange where you may need to adjust the slippage tolerance to account for asset trades that change in value.