I have always found that KVM switches have side effects on USB devices.

So I use mechanical USB switches.

for keyboard and mouse, I use two of these:

https://www.amazon.com/dp/B01I0Y3GEE/

They have no extra keyboard/mouse latency, and no weird side effects like boot keys that don't work or modifier keys that are in the wrong state.

Issues I've had before with mouse/keyboard:

- hotkey conflicts

- mac boot keys break (hold down <key> for <some boot function>)

- modifiers stick in wrong state

- weird delays

- combinations with mouse+keyboard break