MFS, I think that there are two separate issues here.
Rehydration is a significant issue affecting many aircraft types, which has been discussed widely. Many rehydration instances involve control jams or restrictions, which can result in heavy control forces, particularly with servo-tab controls, but assuming correct before-takeoff control checks, problems are not encountered during the takeoff rotation. This issue invariably involves freezing of the water-laden residues during flight.
The problems relating to the thread question (heavy forces during rotation) appear to result from the fluid dynamics, reportedly as the interaction of the deicing-fluid / air flowing over the aerodynamic surfaces (reflex sections) and / or through the tail–elevator hinge gap, thus changing the hinge moment and thence the control force.
AFAIK the problem was predominantly associated with the thicker fluids (type4 or equivalent) which have properties of high dynamic viscosity, i.e. viscosity changes with change of speed of the adjacent airflow.
Lissart, the control forces quoted were maxima.
Manufacturers would normally design a system well below these limits, harmonizing the pitch control system with the roll forces, and allowing a significant margin for a range of wt / cg, and configurations.
IMHO, pilots would be very surprised if faced with the limiting case – cf ATR incident (there was a safety report). This lack of familiarity can cause further problems with requiring the correct use (understanding) of control breakout systems in the event of a ‘mechanical’ jam during rotation. Also, this may lead to an unnecessary rejected take off above V1; again cf ATR incident.