Once in a while, we get stories like this and it’s appropriate givent the holiday season. During a blizzard, Greg and the Gems tell Steven about a story when Steven was a baby. Vidaila had let Greg use her house to take care of Steven. The Gems come by and give Steven presents he’s clearly too young for.
Steven’s gem glows and each of the Gems get an idea about what it could mean. Amethyst thinks is Rose shapeshifting, Garnet thinks Steven is a fusion trying to unfuse, and Pearl thinks it’s Rose trying to communicate. In other words, they all think it’s Rose. They take Steven and find out that Steven is Steven and not Rose and they and Greg agree to figure out things together.
It is established that changing and growing does not come naturally to Gems, though Amethyst has been depicted as younger in previous episodes. This was simply a nice story during the holiday season before yet another hiatus.