tmux.conf excerpt to toggle on/off session keybindings and prefix handling

toggle_keybindings.tmux.conf

bind -T root F12  \
  set prefix None \;\
  set key-table off \;\
  set status-style "fg=$color_status_text,bg=$color_window_off_status_bg" \;\
  set window-status-current-format "#[fg=$color_window_off_status_bg,bg=$color_window_off_status_current_bg]$separator_powerline_right#[default] #I:#W# #[fg=$color_window_off_status_current_bg,bg=$color_window_off_status_bg]$separator_powerline_right#[default]" \;\
  set window-status-current-style "fg=$color_dark,bold,bg=$color_window_off_status_current_bg" \;\
  if -F '#{pane_in_mode}' 'send-keys -X cancel' \;\
  refresh-client -S \;\

bind -T off F12 \
  set -u prefix \;\
  set -u key-table \;\
  set -u status-style \;\
  set -u window-status-current-style \;\
  set -u window-status-current-format \;\
  refresh-client -S
  
wg_is_keys_off="#[fg=$color_light,bg=$color_window_off_indicator]#([ $(tmux show-option -qv key-table) = 'off' ] && echo 'OFF')#[default]"

set -g status-right "$wg_is_keys_off #{sysstat_cpu} | #{sysstat_mem} | #{sysstat_loadavg} | $wg_user_host"

I have 4-time nested tmux session (Because of my work, I have to ssh 3 time to move between networks).

Completely unrelated to tmux, but have you heard of the ProxyJump setting of OpenSSH, @Delt-A ?
For instance, if you have machines named Bastion, Firewall, and Gateway, and Devbox, you set it up ~/.ssh/config like this:

Host bastion
  Hostname bastion.mywork.com

Host firewall
  Hostname firewall.lan
  ProxyJump bastion

Host gateway
  Hostname gateway.inner
  ProxyJump bastion,firewall

Host devbox
  Hostname devbox.lan
  ProxyJump bastion,firewall,gateway

Now you should be able to connect any of these 4 hosts by name, just by typing ssh devbox or the like. I hope you have key-based authentication, so you won't have to type in your password 4 times. You can also override per-host port numbers or usernames, if needed.

If you need multiple sessions at the target machine, you could use tmux, or you could do SSH connection multiplexing. To enable, add this to ~/.ssh/config:

Host *
        ControlPath ~/.ssh/%C.sock
        ControlMaster auto
        ControlPersist 10m
        ServerAliveInterval 1
        ServerAliveCountMax 3

This plugin might be helpful too, it allows you to suspend the local Tmux session: https://github.com/MunifTanjim/tmux-suspend