I wrote a MUD client when I was in high school and for some reason I forgot to document how to quit the app (which put the terminal in raw mode so normal interrupt commands didn't work). And the actual way to quit was completely different from every other application or feature in the client (you had to type Control-Y instead of /quit).

For years I got emails complaining about this. The common solution was to open up another window and send a kill command- except for most people, they weren't using a multiplexed windowing system, just a dumb terminal. So some folks basically got stuck for hours at a time.

Or

ctrl-z

kill %%

That is in tcsh, I would think bash has %% too.

ZZ

Or use tmux/zellij.