bindkey commands run in .zshrc seem ignored when in tmux

- I have some bindkey commands in my .zshrc file which behave as desired. - I start tmux; the same .zshrc is run, including the bindkeys but they don't function. - But then if I manually type them on the command prompt inside tmux, they *do* work again. I've tried with an empty tmux.conf (tmux -L test -f /dev/null) so I know it's not my tmux conf. - zsh 5.8.1 (x86_64-ubuntu-linux-gnu) - tmux 3.2a - Gnome shell (has default TERM=xterm-256color) It's like tmux is somehow resetting the bind keys *after* running my .zshrc? After some testing, I found out that if I remove this line from my .zshrc, the problem goes away:

export EDITOR=which vim

Why?