I just had a look under the cover, where the brake fluid resides.
When turning on the wipers, I can see the fixation slightly move.
All screws are tight, but there seems to be some rubber element on the screw, which gives me the idea, that this movement might me normal.

Is it normal ?

 

Seriously rare the past 70 years and counting for wiper assemblies to NOT be rubber-grommet (or Sputnik..) mounted, regardless of vehicle type, brand, or national origin.