[REG Qt 5.15.2 -> 6.1.2] Cannot Ctrl+Tab from file to file

1. Open two files in Creator.
   Empty text files are sufficient.
2. Press Ctrl+Tab.

Expected behavior, actual behavior with Qt 5.15.2:
The editor changes to the next file. A popup window listing the open files appears and disappears immediately after releasing Tab key.

Actual behavior with Qt 6.1.2:
The popup window appears but does not disappear. The editor does not change files. One can change to the other file by pressing arrow key and Enter. Still, the popup window does not close then.