When I set up a screenshot software, I want to be able to use the shortcut keys directly in the right-click menu, but I cannot activate the shortcut keys in this case
Which screenshot software? How are you activating the shortcuts? More details is needed for us to be able to help you. :) Please see https://community.kde.org/Get_Involved/Issue_Reporting to learn how to file actionable bug reports.
I use Flameshot, but in fact it has nothing to do with the screenshot software. In fact, no matter which global shortcut key is, it cannot be triggered when the menu pops up.
Oh that. :( I'm afraid it's an unfixable X11 bug: in X11, when a menu is active, it steals all keyboard focus, so global shortcuts don't work. This is fixed in Wayland.
That is to say, this error cannot be fixed?
It cannot be fixed on X11 (which is essentially unmaintained and nobody is still fixing bugs). It is already fixed on Wayland.
See bug 70063 (not wanting to mark as a duplicate to send 1000s of mails to users that registered milleniums ago).