On the downforce cars i never noticed any reductions in ride height as speeds grows. This allows to drive the F1 car with rather soft suspension setups.

As the speeds grows, the pressure on the cars with dowforce grows fast, pressing the car down to the track. Its is one of the essentials aspects of setting up a car with high downforce. Setting the springs/dampers soft enough to get the car through slow corners but stiff enough to prevent the car from bottoming out too much on top speed. While doing this one should know the frontend and the rearend of the car will behave diffferent.

In real world, cars are usually setup to have the rear end higher then front at low speeds but at topspeed the rearend gets pressured more down then the front. The result the car will be more horizontal on track at top speed which is good for aerodynamics at topspeed.

I think it would be very nive to have it in S2 fnal or S3.
Disadvantage is, telemetry data is more and more important as the lfs gets more realistic and models more and more aspects of driving. With dynamic ride height its even more important to get the data within lfs, most people dont like it to start up third party programmes after hotlapping.

the effect is there for sure ... all my mechaniked fo8s were bottoming out on the straights all the time

Yep, this is all here.

As for the pitch change with speed on real cars, this would be caused by either "excess" rear downforce (unlikely for most forms of racing) or softer rear springs than front (much more likely).

According to the suspension-damage indicator(F10) cars also bottom out when ride height is set to max, suspension to max and dampers to max. That is not correct, This behaviour is caused by a bug in the damage modelling of the suspension. Even the mrt5 is affected by it, but only mildly because its topspeed is low. But corner it, hit a minor bump and the damage indicators will start flashing.

I did notice g-forces(due to elavations of a track) will correctly bottom out a fast car. But bottom-out due to downforce effects? no i have not been able to notice that effect.