The timely piece in question is presumably titled If You Don't Mask, You Don't Get and notably features a nod to the lyrics of Chumbawamba's 1997 hit "Tubthumbing."
Per a BBC News report, the piece had already been removed by cleaning crews working for the Transport for London agency at the time of the official Banksy Instagram update announcing its existence:
"We'd like to offer Banksy the chance to do a new version of his message for our customers in a suitable location," a rep for Transport of London said, noting that they were appreciative of the mask-encouraging message at the center of the graffiti.
The piece doesn't mark the first time Banksy has expressed creative support for an intelligent response to COVID-19. Back in May, the artist paid tribute to frontline healthcare workers with a painting that depicted nurses among other classic superheroes like Batman and Spider-Man:
The prolific creative also recently showed his support of the Black Lives Matter movement. When announcing that piece in June, Banksy reflected on the responsibility toward justice his position has given him.
"This is a white problem," he said. "And if white people don't fix it, someone will have to come upstairs and kick the door in."