I am having the same issue on PS5
PSN is theuswnt (both servers), I also had the mount on my primary alt account (both servers), as well as my other alt accounts on NA
Yep, same as everyone else, my unlocked Jubilee Confetti mount is gone, all progress reset to zero.
Didn't know this was a bug until I went to use the mount for the Zenithar event, since it's so pretty, then came to the forums for any insight. Anyway, thanks for sorting this out.