Toro Rosso have introduced new sidepods on their STR9, removing the curvature on top of the sidepod in favour of a new, more gradual slope towards the rear suspension. Looking from the back of the car it is obvious what the team have tried to achieve as the hot air exits are now closer to the floor, converging towards a design used by Red Bull and Mercedes AMG. In fact, more and more teams are going this direction as Force India had a similar sidepod update, leaving McLaren to be the only team left with outlets alongside the exhaust pipe.
The move may also have allowed the team to relocate some sidepod internals further down to lower the car's centre of gravity, but thus far the team have not confirmed this.
Also note that the monkey seat above the exhaust pipe as seen in Austria is nothing new and featured on the car at Monaco as well. It seems it was only dropped for Canada due to that circuit's lower downforce requirements.
Despite this looking like a big update, the team's Technical Director James Key noted handily that the updates are a start of a series with more to come at Silverstone and Hockenheim.