As of 10/20/2026 Razer Synapse 4 non-beta (4.0.86.2610120714) causes a double typing problem when synapse is open on the Huntsman V3 Pro 8KHz fullsize, tkl, and the new mini, not the 65% HE (unsure about tkl HE, and non pro tkl). Beta vertsion of Synapse 4 works fine with tkl and fullsize but new mini still has the problem.
When the WASD and QE keys are assigned to gamepad controls and passthrough is enabled those keys double type characters.
Temproray solution: disable hypershift (fn) on gamepad assigned keys and double typing goes away, however Fn+WASD QE will no longer type those letters, not that anyone really cares… By default Fn + any key functions as if that key was pressed (F types F and fn + F types F), except the ones that light up white and have pre-programmed secondary functions at firmware level (J types J and fn + J is page up on Huntsman V3 Pro mini).
For some reason Synapse 4 thinks Fn key is pressed when passthrough fuctionality is enabled, causing the keys to double type. This issue does not occur on factory programed Fn keys that light up white when Fn is held down. For example on the huntsman v3 pro mini 8KHz if you assign UHJK as left thumb stick instead of WASD, because UHJK have secondary factory programmed Fn functions associated with them (Sleep, Home, Page Up, Lower Brightness), they won’t double type.
I hope Razer sees this and pushes out a fix.