A modified version of the default maximize kwin effect done to reduce glitches when using xrender backend.
Related bug: https://bugs.kde.org/show_bug.cgi?id=418247
Video showing the problem (maybe watch it at reduced speed) https://www.youtube.com/watch?v=qKZE6icPHFo
You can install via Systemsettings (effects window).
* Download the archive
* extract the folder present in the tar.gz into your ~/.local/share/kwin/effects/
* from a terminal, start kbuildsycoca5 (or restart kwin, or relogin, or reboot)
* open the effect panel and disable the original maximize effect, enable maximize for xrender