Looking at your inventory, I'd say you synchronized it once and then added more stuff in order to pad it out. Considering you have a Key, striker certified Credits, 50 Gold Rush Boosts, 50 White Hats and a lot of other bogus shenanigans in there, it's not legitimate. The inventory had a few purposes, showing off being one of them (maybe you can do that too, some day), as a premium feature it was also possible to find rather specialized items trough them, even when they weren't listed for trade. For example old decals people didn't bother to put up, or level 250+ Rocket Pass items not that many people got to.