Thank you @David for the solution to this (not enough rep to reply directly inline).
I am trying out Cinnamon on openSUSE Tumbleweed here in the end of 2022.
Every time I tried to exit one of my many favorite curses based utilities (Ex: mc, htop), I was getting the dreaded terminal window menu pop-up despite implementing every solution I had thus far found online (people have been struggling with this for over 10 years as I've seen) over the last two days (gtk.css doesn't sound like the right spot for key bindings, but hey what can I say about cascading style sheets influencing desktop environment keyboard interfaces, maybe some web UI designer had some strong influence on how X11 operates).
Anyway, I had installed the dconf-editor in some prior attempt. Having updated that so I could actually kick it off in the UI with root perms:
-Some other SO post about export $(dbus-launch) to accommodate some gnome requirement business.
The post here by @David gave me the actual path inside the dconf editor I needed.
TL;DR: If you have already updated all the other settings and done that crazy CSS hack to no avail, update the (in dconf) /org/gnome/Terminal/Legacy/Settings/menu-accelerator-enabled option. Changing it in the /org/(all_DEs_here)/desktop/interface location didn't have any affect.
Again, @David: dude I will probably never meet you in real life, but if I do I owe you a pint of your favorite brew for saving me from this keybinding madness.