Solved

Driver Health at 100% Race

Driver Health after 50% of Race = 0.0 losing health rate.
happened to me 2 Races in a Row (since i ve notice) my drivers are not at 20 stamina also they are not at the same level of stamina and their health not at the same percentage when this starts.
At The F1 World Championship
My Team Race 1 Race 2

Thank in advance

This isn't a bug. Drivers stop losing health after completing half of a 100% race. I think the logic here is that they get into a groove at a certain point of the race.