Woah. The rear suspension is unusual. The top control arm is just tiny bit longer with a pick-up point of about 20mm higher than last year. The in-board pick-up points are also mounted higher giving a gentler angle. The roll centre should be higher by doing this, but no point in talking about roll-centre in modern F1 - doesn't matter much.
The real important thing is that the higher and more horizontal wishbones, indicate that they want to keep the contact patch more level by reducing the camber change in squat and bump.
Speaking of squat the plane made by each top wishbone is also less sloped forward. This means there is less "anti-squat" dialed into the suspension. Means a more pliable suspension movement. The Mercedes engineers felt that the new car has a good dynamic weight distribution and stable aerodynamics so they are expecting less rearward weight transfer.
I think these developments are purely for tyre life purposes. The new tyres are much softer this year. This might be the influence of James Allison, who has made cars that were very gentle on their rear tyres.
The other teams like Mclaren, Ferrari have the upper joint closer the chassis with a steeper inclination of the control arm. This inducing a bigger camber change when the suspension is compressed. Good performance in the corners but in squat when accelerating out of the corner the contact patch is smaller heating up the tyres more.
I expect Mercedes to have slower tyre warm up this year but monstrous stint lengths. No problem when you are racing from the front.