Merc are shocking tbh, season's definitely a right off now and maybe next year, they've shown they haven't got a clue.
Mind you the fezzas looked terrible as well, as said above these cars are not fit for purpose (porpoise)
Every team, to some extent or other, is suffering from porpoiseing.
It is virtually impossible to completely eliminate it under current regulations.
It is far too much of a factor of the entire chassis design, if the natural frequency of the chassis (every teams design will have a different natural frequency) is the same as the frequency of the porpoiseing created by the areo stalling and re-engaging, that is when you get the really terrible bouncing..
That is not changeable within a year, and will only be eased when the new car is designed and built for next year.
The ONLY way to completely and utterly eliminate it under any and all circumstances, is the way it was eliminated in the past when ground effect was used, and that is by fully active suspension, which has been banned, although there are some rumblings and rumours it could be allowed again, if it continues to be an issue in future years.
All any of the teams can do currently is manage it as best as possible.
Some teams, RBR mainly, and Ferrari to a lesser extent, still get great performance even with quite high ride heights, so they can get away with minimal porpoiseing, although it is definitely still there, although at different times and speeds to other teams, due to differences in chassis design.
Others such as Mercs, loose too much performance when running high ride heights, so have to try to balance between performance and ride quality, and that results in far more obvious porpoiseing.