So it looks like a few teams are hitting an unexpected issue that didn’t turn up in simulation. Porpoising.
Basically the ground effect gets caught in a loop of suction then losing suction as the aerodynamic properties change. The car bounces from rear to front and loops in this manner continuously.
It can damage the floor and obviously it’ll affect handling and vision. It’s so bad it’s actually damaged the track to the point where Sainz was seen avoiding the bumps on the racing line on the main straight.
It’ll be interesting to see what they do to mitigate the issue. It goes to show that we’ve still got limitations in even the most expensive and sophisticated simulation.