gnome-terminal Alt+<Number> is not working

[Mingun]

In Ubuntu 20.04.2 key accelerators Alt+<Number> is not working -- instead of changing the current tab the string "^[<Number>" is printed to the current console. See the screenshot attached

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-terminal 3.36.2-1ubuntu1~20.04
ProcVersionSignature: Ubuntu 5.4.0-71.79-generic 5.4.101
Uname: Linux 5.4.0-71-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Apr 8 09:14:02 2021
InstallationDate: Installed on 2020-11-24 (134 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-terminal
UpgradeStatus: Upgraded to focal on 2020-11-25 (133 days ago)

[Mingun (alexander-sergey)]

Other shorcuts, for example Ctrl+Shift+T (open new tab) is working

[Mingun (alexander-sergey)]

Found similar problem in the Gtk bugtracker: https://gitlab.gnome.org/GNOME/gtk/-/issues/2174

This bug is fixed when key mnemonics is disabled (see the screenshot)