I can't provoke your problem. I also have Android 11 and QPG 8.3SERIOUS QuickPic Gallery 8.3 bug with Android 11.
If I crop a photo on my SD card with QuickPic Gallery and then use QuickPic to move the cropped photo to a different folder on the SD card, the photo just DISAPPEARS. As far as I can tell, this only happens if you crop a photo and only on the SD card. I have lost numerous photos before discovering this bug.
I first tried to report this on the WSTxda chat on Telegram, but when I tried to access the chat, it said that an admin had banned me. There is absolutely no reason for me to be banned, I am not sure I have even ever used that chat channel before. This is a particular kick in the teeth, since I have gone out of my way to assist people in this thread, due to my prior love for this app.