To improve the success rate of private trades, it is recommended to set a private swap Slippage Tolerance as protection in case of slippage. This will reduce the amount of private tokens earned from the trade, but the part not consumed by slippage will be returned in the form of public tokens.
Any portion unused in a transaction "wear part" will be refunded to your specified address as public tokens. For added privacy in your transactions, consider using an alternate wallet address.