How mysterious! It's possible the default USB drivers changed and the mic is now at a higher gain than it was (regardless of the volume slider). Generally, pickup of ambient sounds is directly related to the overall gain of the mic. Uni-mode should decrease ambient noise slightly, but keep in mind the mic is more sensitive in Uni mode than Omni, so you have to both swap modes and decrease the volume slider to get the effect. (Admittedly, this was a design error).
If you hit up our Discord we can probably go over streamlining the gain to the right level:
https://discord.gg/Jn6x7uc
One thing we can talk about as well is simply setting up a noise gate that will prevent that sound from getting through when you are not talking at least (Ideally, your voice will overpower it when you ARE talking, so people won't notice much).
The nuclear option is to try to filter out the frequency bands of the mouse and keyboard, but they are far more complex sounds than you may think, so the impact of this will be minimal and potentially reduce quality severely.
Happy to help you live in our discord, just tag me @AntlionJoe.