According to Footy Headlines, the Nike Barcelona 2020-21 away shirt will be predominantly black, likely paired with golden logos.
This brings back memories of 2013-14 away shirt, which was a popular one with the club's fans.
Unfortunately, no design specifics of the FC Barcelona 20-21 away shirt are known as of yet. The Nike Barcelona 20-21 away shirt is set to be launched in June or July 2020.