A high-foot isn't always a foul. But considering how there were both Otomo and Aoi around Tripone, it would usually be considered dangerous play. And even if it could be debated that since Aoi didn't appear to be competing for the ball, Tripone could get away with it, but if one pays attention to the preceding panel, it can be noticed that the ball appears to be falling in front of Aoi; unless Tripone managed to shove Aoi away or push his way in in an instant, it would be impossible for his foot to reach the ball without it going over Aoi's head, and that too with the bottom of his shoes facing Aoi's head which would undoubtedly be a dangerous play.
And that's not even considering how Tripone manages to bring down the ball with the back of his foot-usually considered impossible.