In the crime-thriller movie, The Stranger (2022), in a dream scene, the undercover police officer drives his car with Henry (the suspected child kidnapper/murderer). All of a sudden and seemingly unrelated to their current conversation, Henry shouts: "I've got a black lake in my eye!" in a distorted and devilish voice (serving as a jump scare).
What is the significance of this line of dialogue? I thought it would be a religious reference, but have not found anything.