as mentioned in [RELEASED] Discus-2c | Got Friends - #137 disabling slew mode should set initial airspeed when height is greater than 0. If aircraft is not on the ground but in the air, initial speed could be 1.3*Vs0 (stall speed for landing). It will avoid aircraft stall when disabling slew mode. If aircraft is on the ground, ground speed should be set to 0.
I think that, currently, initial speed is preserved when setting flew mode on and off. This is not an issue if aircraft / glider have an airspeed beyond stall speed but it’s really problematic when doing this at airspeed below Vs0
I think some misunderstanding happened. By default, airspeed set in FLT file and chosen by sim depending on situation. Usually (but not always) works fine but not in Discus - I even tried to replace FLT content from other aircraft but it didn’t helped.
So its not really global MSFS issue but specific Discus problem.