Ju-88 "toe brakes" work proportional - if assigned to analog axis.
Try adjust sensitivity... But does not seem to be the case.. your screen show clear a "ON/OFF" like a button press.
You have "Slaw Pedal"?
his one have digital sensors for rudder/brakes, perhaps the game see signal as press.
Strange is OK for one plane and not for another...
Sokol1