I second this. I wouldn't have been able to make tmux such an integral part of my daily workflow if it weren't for this binding that I came across in someone's starter tmux conf many years ago.

jj or qq can also be used. As I once started with GNU Screen ages ago, I like prefix to ctrl+a but it interferes with going to front of command in bash mode. For that, I use vi keybind mode in my shell (fish or bash) which feel very natural to me. For zellij, I use default prefix so that it does not interfere with remote (yes I am aware remote requires double prefix; I prefer using tmux remotely and zellij locally).