I'm not sure if this is standard on the T7 (I couldn't find anything about it in the FCOM). During VNAV descent, I noticed that my armed speed brake was automatically moving itself between the armed and unarmed detents. While I may be mistaken, the activity "seemed" to be associated with the appearance and disappearance of the DRAG REQUIRED FMC notification during a VNAV descent. Once I was in APP mode, the problem self-corrected. Admittedly, the speed brake was armed early in the approach procedure. However, I just thought it a little odd that the lever would move itself and wondered if this mirrors the true operation of the speed brake and/or if anyone else has experienced this phenomenon.

It is most likely your hardware thrust levers causing it. It's a calibration issue I think and I have it as well but I can operate the speedbrake just fine

Click the spoiler handle with your mouse, Also the above.

Insert a small null zone on the axis in FSX.

To answer your question, this has nothing to do with the DRAG REQUIRED message...

As the posters above said, most likely it's your hardware calibration. Sometimes FSX assigns 2-3 inputs on 1 axis, double check your hardware(s) have properly assigned axis, in case double assignment delete the extra. Furthermore check your FSUIPC config if you have it.