SUMMARY
Shortcuts that use Shift and numbers (for example, Meta+!/Meta+Shift+1) are misrecorded by Global Shortcuts, causing them to not work.

STEPS TO REPRODUCE
1. Open System Settings
2. Click on Shortcuts > Global Shortcuts
3. Select any application or service (for example, KWin)
4. Assign a custom shortcut that uses both Shift and a number to any action (for example, assign Meta+!/Meta+Shift+1 to the "Maximize Window" action)
5. Click Apply
2. Press Meta+!/Meta+Shift+1 on the keyboard to perform the action

OBSERVED RESULT
Nothing happens

EXPECTED RESULT
The action should be performed

ADDITIONAL INFORMATION
The new Global Shortcuts KCM is recording inputs such as "Meta+Shift+1" as "Meta+Shift+!", which causes them not to be activated by KGlobalAccel, which is expecting inputs such as "Meta+!".

I have verified this by manually editing the ~/.config/kglobalshortcutsrc file and removing the Shift modifier from the shortcuts created on the Global Shortcuts KCM. After restarting the session, the shortcuts worked.

I also downloaded Kubuntu 18.04.4 to see if this issue was present in the old Global Shortcuts KCM. This version of the KCM recorded the "Meta+Shift+1" input as "Meta+!", and activating this shortcut performed the action without problems.

SOFTWARE/OS VERSIONS
Linux distribution: Arch Linux
KDE Plasma Version: 5.19.2
KDE Frameworks Version: 5.71.0
Qt Version: 5.15.0