I've now tried both a brand new Z20 and a brand new X15 on two different computers are they're both very hosed up. It doesn't happen all that often, but when it does, I'm pretty much unable to do anything shy of rebooting. One of my machines are running Windows 11 and one is on Windows 10. The X15 firmware is: v1.42 and the X20 firmware is: v1.34. Also the EVGA software version is: v1.0.17.
It's very difficult to duplicate the errors as they seem to happen rarely, but when it does it appears to only happen if I have both the Elder Scrolls Online open as well as a Youtube video via Brave browser. I'm still trying to test this to confirm if it only happens when both of those are open, but as I said below, it's very difficult since it's random only.
As far as resolving it. When the mouse disconnects, I can unplut it, wait 5 seconds, plug it back in anywhere from 1-5 times and it seems to resolve the issues. For the keyboard though, there doesn't appear to be any solution other than a full on reboot. Closing the EVGA software and reopening it does nothing. When the keyboard messes up, some functions and keys work fine, such as CTRL+ESC, tab, Win+E, and some others. However, others just stop working completely such as all alpha numberic keys. It's basically acting like my CTRL key is getting stuck, except on a software level, not a hardware level as the keys are physically fine (and brand new) on both keyboards.
This is extremely annoying and I'm sick of dealing with it at this point.