emacs-pgtk-git 30.0.50 not recognize kbd "S-SPC"

[Hu Elliott]

Hi, I switched my emacs from x window-system (ver 28.x) to pgtk window-system 
(ver 30.0.50) for native wayland support (my WM/DE is SwayWM).

But I can't bind "S-SPC" to a function (yasnippet's "yas-next-field") anymore 
because emacs won't recognize "S-SPC" (i.e. <shift> + <space>).

Here's futher detail:

1. switched to x window-system emacs (ver 28.x, stable release)
 a. run "emacs -Q"
 b. press "C-h k"
 c. press "S-SPC"
 d. result (please notice the "translated from S-SPC"):

SPC (translated from S-SPC) runs the command self-insert-command
(found in global-map), which is an interactive built-in function in ‘C
source code’.
...

2. switched to pgtk window-system emacs (ver 30.0.50)
 a. run "emacs -Q"
 b. press "C-h k"
 c. press "S-SPC"
 d. result:

SPC runs the command self-insert-command (found in global-map), which
is an interactive built-in function in ‘C source code’.
...

As I rely on this key binding heavily to jump through tab stops in my snippets 
(thousand times per day), I really need "S-SPC" to be recognized again. Your 
help is highly appreciated.

Thank you.