The founder of Litecoin recently pointed out that unspent transaction outputs can have a negative impact on the fungibility of Bitcoin. Fungibility refers to the ability of a cryptocurrency to be interchangeable with another unit of the same value. When there are unspent transaction outputs, it can create a lack of privacy and potentially lead to a loss of fungibility. This issue highlights the importance of addressing such concerns in order to maintain the integrity of Bitcoin as a digital currency.