Keyboard oddities: backspace creating block square, H key deleting, most keys not working

I had 5 servers where the keyboard was not responding correctly. If I remember I seemingly had the most trouble in Windows, I don't remember if the linux or ESXi server was having troubles. I had two cheap KVM's daisy-chained together, recipe for disaster. Things I had tried unsuccessfully:

• I knew the keyboard was working as Backspace produced characters in the password field & H key deleted them
• Connect a known-good USB keyboard
• Disconnect daisy-chain & use just one KVM
• Disconnect KVM & try known-good USB keyboard again

I am posting this to maybe help someone else or my future self from pulling out your hair. Since I look to this site for a lot of issues, I thought it should go here. I know it may be a one-off situation, but upon looking online many others had similar issues

Solution 1:

Pressing the left Ctrl key solved it for me. My guess is the daisy-chain KVM's caused it, a cable was probably loose & one of the PC's interpreted it as a keystroke. The oddity is that it happened on multiple servers & disconnecting the keyboard & trying a totally different one didn't solve