CTRL-V_CTRL-[key], instead of ^[key] gives ^[[27;5;[ASCII code of key]~ in xterm on Arch

Question

For example, Ctrl-v_Ctrl-w gives ^[[27;5;119~ instead of usual ^W.

It does behave in such way only on (u)xterm. I've tested it on st, lxterminal, xfce4-terminal and rxvt. I'm also 98% positive that it works fine on konsole and gnome-terminal (based on this post).

Furthermore, xterm on Ubuntu doesn't have issues. Only on Arch.

Outside Vim everything also is normal (i.e. ^W). Neovim doesn't have such problem either.

Does anybody knows what could cause such behavior?

Specification:

• Distro: Arch Linux
• Kernel: Linux alpha 5.3.12-arch1-1
• xterm: 351 (but also occurs on 348)
• Vim: 8.1.2268-2 (and 8.1.2337-1)

Related problem

While it's highly unrelated (vim -u NONE also doesn't work properly), but my configs:

• vimrc
• Xresources

Answer 1

As of patch 8.1.2350, Ctrl-V will emit again the translated key, even if modifyOtherKeys has been set. To get the raw escape sequence, you can instead use now Ctrl-Shift-V

Answer 2

set t_TE= t_TI=

This in vimrc disables modifyOtherKeys (:h modifyOtherKeys), which was causing the problems