Using scanner input IRcode will result in an error when second character is uppercase

I have a scanner, When using a Qt program to input, if the second character is uppercase, the first lowercase character will be converted to a character with shift during the first scan.

On my computer, using xdotool I can also reproduce this phenomenon. see error.mp4 and xdotool.sh

the video show the reproduce step:

1. open a Qt program and type some character to make sure the keyboard is master device;
2. then run xdotool.sh and active Qt window, select QLineEdit all text, wait xdotool input;
3. you will see the first character is error.

note:

a. reproduce this bug to make sure the second character is uppercase;

b. xdotool sometime maybe can't reproduce,but scanner always exist.

Process analysis：

1. when use xdotool or scanner input, first of all, xorg-server will call CopyKeyClass and send XkbSendNewKeyboardNotify event to Qt program;
2. when Qt program recvice this event, Qt will call updateKeymap, see Qt code: qtbase/src/plugins/platforms/xcb/qxcbkeyboard.cpp updateKeymap function;
3. in the updateKeymap function, Qt will call libxkbcommon to reset xkbState, and this time, libxkbcommon will return Qt a new xkbState, but the value base_mods of xkbState's is not right;

note:

If you switch input between the keyboard and the scanner, this bug will reappear immediately

My guess:

1. When xorg-server send XkbSendNewKeyboardNotify event, Qt and libxkbcommon communicate will spend some time;
2. If Qt didn't initialized yet, and shift if pressed, and this time xorg-server will give libxkbcommon a error base_mods value of xkbState's.

note:

a. If you increase the scanner input delay between characters, the probability of recurrence will decrease；

b. If xorg-server not send XkbSendNewKeyboardNotify event, this bug don't reproduce;

c. if xorg-server send XkbSendNewKeyboardNotify event, but Qt do nothing, this bug don't reproduce too;