Applies to weapons with selectable zoom magnification levels: Vectis (Prime), Rubico (Prime), Veldt, Vulkar (Wraith), etc.
When being scoped in (or adsing, aiming down sights) with a weapon with selectable zoom levels, hitting "Switch Weapon" key results not only in intended result (switching the weapon) but also changes zoom level of the sniper rifle - the functionality of changing zoom magnification level prior to this bug was only present under the "Secondary Fire" key (which should be the only way of switching zoom levels).
Worth noting is that thae bug ONLY applies to weapons which secondary functionality (as evoked by pressing "Secondary Fire" key) is the zoom magnification levels. The bug does not affect weapons which secondary functionalities are, for example: switching fire modes from burst to auto and vice versa.
This being said, the weapon like, for example, Kuva Hind, which has 3 fire modes selectable by "Secondary Fire" key, is not affected by this bug. Pressing "Switch Weapon" key doesn't result in fire mode being switched.