According to the search results, Sylvie is holding a glowing object that is He Who Remains TemPad device. This device combines the qualities of a TemPad, which generates timeline-crossing Timedoors for its users, and a Time Twister, a teleportation device often used by the TVA. Sylvie presumably took the device after killing He Who Remains at the end of Lokis first season. The fact that Sylvie is in possession of the device proves that she is a Loki, as Loki would probably also pocket a device like that.