what is likely actually happening is your fov is lowering and you're sensitivity does not scale with it making it feel very fast. really hope they fix soon. as a temporary fix they could just stop lowering your fov and it'd feel much better. or just scale the sensitivity with the fov.
Using moves such as "Lethal Venom"/ 2 on vyper disables firing you're weapon if you're using quick cast even after you're finished casting the ability. Instant cast does not have this issue, I understand there may be a state issue at play here being the casting state doesn't allow for shooting...
