Plasma 6: Task manager panel leading and trailing spacing
With Plasma 6, the task manager panel is floating by default, and snaps to the edge of the screen when touching a window. Users can also disable the floating behaviour and keep it always snapped (which is my personal choice).
When the panel is floating, the entries are evenly distributed as expected. However, when it is snapped to the edge (either automatically or by disabling floating), it seems that the panel's horizontal extent remains smaller than the width of the screen, and that space at either end is filled with some extra material. This results in entries towards the left and right ends of the panel not quite reaching their respective corners of the screen.
Illustration: Snippet of my screen. The Application Launcher icon is not perfectly centred between the left end of the screen and the next entry (Virtual Desktop widget), the gap to its left is slightly larger than the one to its right (it's quite subtle, and needs a close look). Similarly, my rightmost entry (date and time) looks slightly more to its left than it should be.
In Plasma 5, the gap on the outward side of the left-/right-most entry was the same size as the gap on the inward side, and not slightly larger as seen here. The current behaviour results in wasted space on the task manager panel and also spoils the look by creating asymmetry.