This version backports new features introduced in plasma6 branch.

Changelog:

Includes a fork of KWin Blur effect to fix the "korner bug" on X11 and Wayland
The settings for outline width and color were added
Works with any window decorations
- Shadow offset parameter can solve issues with window decorations outlines
Window shaping does not use additional textures and is done entirely in shader, which potentially improves performance

Notes:

This version includes a patched KWin Blur effect, that shapes blur region using the lshelper library that also comes bundled with this plugin. To build it in Plasma 5.27.10, some KWin headers were included and an installer script introduced, which makes a symlink to libkwin.so.5. This is needed, because KWin development packages for Plasma 5.27 does not include that (which is not the case in Plasma 6).
To build this version, you will need to install qt5, kf5, kwin and xcb development packages.