I have an issue with the AltGr+Key combinations in VIM

On a German keyboard, characters like {[]}\@|~ must be entered using AltGr.
For example, { with AltGr+7 and } with AltGr+0.

This works without any problems in WindTerm when using the Linux Bash.
However, when I start VIM or NVIM in the same Bash session, the AltGr key stops working.
Instead of the expected characters, special sequences like <9b> appear.

I tested with other terminals (MobaTerm, Windows Terminal). They do not show the issue on the same server.

I love WindTerm. You’ve done a fantastic job!
If this issue gets resolved, I can fully switch to WindTerm.

Version: WindTerm 2.7.0 Prerelease 3
OS: Windows 10

TERM=xterm-256color
LANG=de_DE.UTF-8

Start by reproducing the German keyboard AltGr combinations in Vim and Neovim through the Linux Bash session described, then compare the input behavior with WindTerm's normal Bash mode and other terminals. Done means characters such as {[]}\@|~ are entered correctly in Vim and Neovim instead of producing sequences like <9b> under the stated environment.

Written by the indexing model from the issue text.