No "apl-z" by C-\

[Sokleidas]

M-x gnu-apl
C-h v default-input-method

default-input-method is a variable defined in ‘mule-cmds.el’.

Its value is "german-postfix"
Original value was nil

Default input method for multilingual text (a string).
This is the input method activated automatically by the command
‘toggle-input-method’ (C-).

You can customize this variable.
Probably introduced at or before Emacs version 21.1.

[back]

M-x cu-var default-input-method

Hide Default Input Method: Choice: Value Menu String: german-postfix
State : CHANGED outside Customize.
Default input method for multilingual text (a string). Hide
This is the input method activated automatically by the command
‘toggle-input-method’ (C-).
Groups: Mule
See also Manual.

Shouldn’t we expect "apl-z"? I’m not setting default-input-method anywhere in my startup files. Perhaps what is said in chapter 23.2 of the Emacs manual applies. I’m running Emacs on Ubuntu 22.04.

GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.33, cairo version 1.16.0) of 2022-10-26
gnu-apl-mode-20220404.341

Any help is much appreciated!