I'm not a Bungie Employee, but anecdotally I've seen a Bungie Employee reply that it's a known issue, apparently they're forced to use two separate rendering engines for the game and the app / website for complicated technical reasons he didn't care to delve into which can result in slightly different versions of the same armor piece. Hopefully they'll be able to find solutions to those technical problems going forward, thanks for taking the time to share your thoughts.