@Bts#Army_Butter_Special_performance.

As of my last knowledge update in September 2021, I'm not aware of any specific "Butter special performance" by BTS or any related details. However, BTS often releases special performances, dance practices, and versions of their songs on various occasions. If they have released a special performance of "Butter" or any other song after that date, I recommend checking official BTS social media accounts, their official website, or reliable sources to get the most up-to-date information and descriptions of their performances.