Answer by Kamil Maciorowski for tmux - How to change text color of current pane to yellow if pane is in copy-mode

Moving to another pane does not trigger pane-mode-changed, it triggers window-pane-changed. The simplest improvement is to define two hooks:

set-hook -g pane-mode-changed   '…'   # you already have thisset-hook -g window-pane-changed '…'   # same action, different trigger