Recently BCHA, YFV and BZRX have migrated contracts and currency ticker symbols. We will be delisting and removing these now defunct tokens from Poloniex in an effort to clean up our interface. As these currencies have migrated to new tokens, the old tokens no longer exist, so there is nothing that is required on your end, this is simply an exercise in good housekeeping.
All users who held these tokens have been credited with their new tokens.
January 28, 2022