The command+R hotkey in iTerm2 is bound to "Reset" the terminal window in the top level menu.
I kept hitting it when I thought I was in my browser and was trying to refresh it. The result is it kept clearing nvim which was a pain.
Luckily, this can be disabled. The fix I used was to go into System Preferences < Keyboard < Shortcuts and then add iTerm2 as an application with a remap of "Reset" to command+8. That overwrites the ability to jump directly to the 8th tab. For some reason neither it or the reset work, but I'm fine with that.
I just wanted to prevent the reset which is what it does with this in place.