Sierra (Cierra Ortega) left the Love Island USA villa due to a "personal situation" related to the resurfacing of her past social media posts that contained racist slurs aimed at Chinese people. The producers told the cast that she had broken some of the show's policies, which led to her removal from the villa. This exit was not voluntary; it was a decision by the show based on the controversy of those posts. Cierra's departure left her then-partner Nic Vansteenberghe single in the villa, and he was upset by her leaving but did not know the full details at the time. Cierra later addressed her exit and expressed regret over the situation, acknowledging that her past actions had serious consequences.

In summary, Sierra left the villa because she was removed by the producers due to violations related to past racist posts on social media that resurfaced during the show.