Created attachment 186153 [details]
Demonstration of the bug with Dolphin and Firefox

SUMMARY
Since 6.5 there is a strange behavior of Icons-Only Task Manager (might affect the other one also, I don't use it though) when using drag-n-drop on an application with multiple windows open. When I drag e.g. a file from Dolphin onto the icon of Firefox with 2 browser windows open, there is a list of all the windows open that pops up above the icon, naturally I move the file dragged file on top of the window title which I wanna drop it in, but for some reason there is now a gap between the task manager and the list, so dragging the file towards the list hides the popup.
This is a very strange UX design and a regression compared to the UX of 6.4 and should be reverted (if intentional) or fixed.
Note that I'm aware of using the arrow keys and enter to navigate the list, but that isn't a comfortable nor intuitive for the average user.

STEPS TO REPRODUCE
1. Have Icons-Only Task Manager in a panel.
2. Have Dolphin open with a file ready.
3. Have a program supporting drag-n-drop (e.g. a web browser) open with multiple windows.
4. Try to drag-n-drop from Dolphin to the program.

OBSERVED RESULT

Attempting to reach the list with the mouse hides the list because of a gap.

EXPECTED RESULT

There should be no gap and you should be able to reach the list with no problem with mouse only.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.5.0
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.17.4-4-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 16 × 11th Gen Intel® Core™ i7-11800H @ 2.30GHz
Memory: 32 GiB of RAM (31.0 GiB usable)
Graphics Processor 1: Intel® UHD Graphics
Graphics Processor 2: NVIDIA GeForce RTX 3060 Laptop GPU


ADDITIONAL INFORMATION