Tua is doing exactly what he's been doing since day one. If his first read is there he'll identify it and deliver the ball accurately. In that sense the Shanahan offense is perfect for him because it's mostly a one read offense. That system combined with all of that speed really just needs a one read QB that can get the ball out on time. It's the same reason San Fran is making it work with Brock Purdy.
If you want to stop the offense, take away the first read and take away the middle of the field. Much easier said than done of course.