Yes, in the Boo Arc. Granted, he technically wasn't Piccolo at that point beyond name due to his sense of self-identity having changed fully after fusing with Kami, but the way in which he acted uncharacteristically goofy during the arc and had fully resigned himself to being a side-character was far from a natural progression of his character up to that point.
Including Super, he's definitely been flanderised throughout its entirety, announcing himself as the reborn demon king against Frost in the manga being a complete regression from what he's achieved all for the sake of a cool line that makes it apparent how much Toyotaro doesn't understand DB's characters as well as being so incompetent as to be caught off-guard by Damon despite his hearing being exceptional and that being the very sense #17 uses to find Damon.