With a FF stick like G940 (with a piece of tape covering the optical grip sensor) you don't get the bump because the stick will physically remain in the trimmed position instead of going back to center vertical position even if you let go of the stick after trimming....as in the real KA50.
However, there is still a bump for rudder trimming even for FF users because there is a bug where central trimming mode doesn't work for the rudder when FF is enabled for the joystick (central trimming mode gets disabled even for rudder when FF is enabled for joystick). For rudder, as soon as trim button is released, it adds the amount of physical rudder displacement instantaneously to the trimmed amount causing the bump. I reported this to ED many years ago but it was ignored most likely because they didn't understand what I was trying to say.
At any rate, all of this is moot for G940 users right now with latest version of DCS currently due to another unrelated trim axes bug where the work around is to disable FF....