Mika, not to hijack the thread from @JonSton but I did have a similar thing happen to me yesterday. I didn’t think much of it until seeing this thread.
I was hit from behind quite hard by the AI in rF2 and after coming to a stop and then moving off again, I noticed that the FFB strength had been greatly reduced. I did still have full control of the wheel though.
I thought it was maybe some kind of safety feature that automatically disabled high torque mode so I alt/tabbed to look at TD settings and noticed that high torque mode was still in fact enabled even though the strength was pretty much down to zero.
I then disabled and then re enabled high torque mode and everything came back to normal.
Just wanted to chime in, in case the information may be of help.