Fish shells cannot use the kitty keyboard protocol

[Su3h7aM]

Issue description

I am testing the 4.0 beta version of fish, which has added several features, including the ability to use line breaks using shift-enter, which works perfectly when running fish directly in kitty, but not when zellij is in between.

Minimal reproduction

Use fish_key_reader to check pressed keys,
press ctrl+shift+l.

kitty -> fish

kitty -> zellij -> fish

Other relevant information

OS: CachyOS Linux x86_64
Kernel: Linux 6.12.6-2-cachyos
DE: KDE Plasma 6.2.4
WM: KWin (Wayland)

kitty --version
kitty 0.37.0 created by Kovid Goyal

zellij --version
zellij 0.41.2

fish --version
fish, version 4.0b1-13-g541f8b47b