YandereDev, the creator of Yandere Simulator, was originally intended to appear as a playable character as part of Monsters & Mortals' crossover DLC with Yandere Simulator. However, his inclusion was scrapped due to the developers feeling it would be out of place, given that the Yandere Simulator DLC was intended to focus specifically on Yandere Simulator itself. Despite this, some fans believe that YandereDev's removal was due to various controversies surrounding him at the time.

On September 17, 2023, the official Dark Deception: Monsters & Mortals Twitter account revealed that there were plans for a crossover DLC pack based on the game Murder House by Puppet Combo, but that said plans fell through for unknown reasons. A pitch trailer for the collaboration was also uploaded as part of the tweet.

On September 18, 2023, it was revealed on the Dark Deception: Monsters & Mortals Twitter account that a pitch had been made for a DLC pack based on Catherine: Full Body by Atlus, but that said plans never materialized. A mockup trailer was also released, suggesting that said pack would have featured Vincent Brooks as a playable character and would have released in 2021, had it been accepted.

In late 2023, Yandere Simulator creator YandereDev was accused of grooming a minor after the person in particular revealed several screenshots and audio recordings between them, prompting some of the game's developers and voice actors (including Michaela Laws, the voice of main character Ayano Aishi) to leave the project. On top of this, three games that had previously crossed over with Yandere Simulator severed ties with the game:

• Glowstick Entertainment ended all future sales of Dark Deception: Monsters & Mortals' crossover DLC with Yandere Simulator, as well as officially cancelling Ayano's Lovesick Labyrinth (a planned crossover between Yandere Simulator and Dark Deception, previously shelved).
• Sad Panda Studios announced that they would be updating Crush Crush in order to replace Ayano (who had been added as a guest character) with an original character named Ayeka.
• xDNA replaced the guest characters Ayano and Info-chan with reskinned original characters named Patti and Emily respectively.