A firm explanation has never really been given as to why the show was canceled, but the cancelation did occur shortly after Adult Swim’s then-CEO, Mike Lazzo, retired and was replaced by Michael Ouweleen.

Source: https://www.themarysue.com/the-venture-bros-movie-release-window-cast-plot-and-more/

Arlecchino has been mentioned in multiple voice lines, and she finally made her first appearance during the "A Winter Night's Lazzo" trailer that also revealed all the remaining Harbingers.

Source: https://gamerant.com/genshin-impact-arlecchino-weapon-type/