Virtual Keyboard not appearing after certain unrelated events

We've been having issues on our NXP imx8 device where the virtual keyboard works fine until the screen goes to sleep. When we wake the screen back up, then the virtual keyboard no longer works.

We were able to duplicate this with other, more common hardware. 

Here's how to duplicate it on on Raspberry Pi 3:
step 1 : Boot to weston on Raspberry Pi 3
step 2 : Run attached test tool (FastBlur.zip)
step 3 : Plug in a mouse and touch screen on Raspberry Pi 3.
step 4 : A virtual keyboard will appear on the screen.
step 5 : The user can enter some words through virtual keyboard.
step 6 : Unplug a mouse.
step 7 : A virtual keyboard will disappear from the screen. When user touches the textbox, a virtual keyboard cannot appear again.

We have this issue in Qt6.3.2. We noticed that our older Qt5.15-based builds don't have this issue and narrowed that down to a virtual keycode (power button) in the device tree. (please refer the attached file). NXP's older Zeus-based EVK BSP has this virtual keycode in the device tree, whereas the newer Kirkstone-based BSP does not. If we remove this virtual keycode from the older (Qt5.15-based) image's device tree, then this same issue appears in Qt5.15 as well. 

But adding this virtual keycode in the device tree seems like a workaround that is not very intuitive. Why is the Qt framework disabling the virtual keyboard after a USB mouse is removed?