Inconsistent behaviour on decorations between `--select` and `--geometry`
On KDE Plasma, when using maim --select and selecting a window, the window decorations are replaced with part of the screen contents (apparently, relative to where the selected window was originally spawned). The problem seems to happen with any application.

(Here, the content of the top of the screen is being shown instead of Alacritty's title bar.)
By using maim --geometry $(slop), the problem does not occur.

The problem also happens on the whole window border when they are enabled:

maim --version is v5.5.3; slop --version is v7.4.
It seems this is related to the way KDE renders its window decorations. If I use maim -s it correctly ignores all windows behind behind a transparent window.

However, you can see the background when using maim --geometry $(slop).

When using the maim -i $(xdotool getactivewindow) command, which should only screenshot the active window, it fully ignores the window decorations.

This makes me believe that this probably can't fully be resolved with the way KDE handles these decorations, and might have to be a trade-of between privacy of underlying windows and screen decorations when using maim on KDE.
However, I have not looked into the actual code and hope to be corrected!