R. L. Stine’s The Haunting Hour Season 1 Episode 20 123movies

Josh always knew that Matt was the perfect son in the family. But when Matt’s star begins to fade, Josh thinks that what his parents propose may be taking things to the extreme. It is revealed in the end that Matt is actually a robot whose warranty has already expired, causing all the bizarre changes. After being replaced, Josh finds out that Matt wasn’t the experiment. As Josh is about to be shipped away, his parents tell them that they are robots as well and that her was the experiment, not Matt.(which ends with a possibility that Matt is a robot himself as well but with emotions)