Since the new patch went out, using Toggle raise weapon (default 2x left ctrl) while moving to lower a weapon causes the player to stop, do an arm swing as usual when moving with weapons down, place his hand back on the weapon, and then continue moving. In previous versions, this never happened and the motion was always smooth.
Notably, using 2x left ctrl again to bring the weapon back up doesn't cause any issues, but using LMB does, causing the player to stop and bring the weapon up before moving again.
This happens with both rifles and sidearms (reversed when using sidearms. Using LMB to raise doesn't cause an issue, but using Toggle raise weapon does)