This wiki article provides insight into various specificities or questions about the Mokka Theme, not referenced in the Release Article.
Mokka installs as a dependency the package kwin-effects-forceblur. This is different than the default Blur effect included in Plasma. It provides of course blur effects on windows, docks and menus, but also allows control over which of the 3 blurs and uses an include/exclude list of Window Classes. For example, with this feature we are able to not blur docks and exclude window class xwaylandvideobridge apps, which should not blur.
However according to the source, it could be resource-intensive, especially if you have many windows open.
On Wayland, high GPU load may result in higher cursor latency or even stuttering. If that bothers you, set the following environment variable:
KWIN_DRM_NO_AMS=1.
If that’s not enough, try enabling or disabling the software cursor by also setting:
KWIN_FORCE_SW_CURSOR=0
or KWIN_FORCE_SW_CURSOR=1.
Intel GPUs use software cursor by default due to this bug, however it doesn’t seem to affect all GPUs.
Also in some situations with some types of installs (hardware, software, configs, etc.), you may find yourself having the old KDE bug that displays a triangled shadow around the corners of the Window Decorations.

It is possible, but not guaranteed, setting the Anti-aliasing, located in the Rounded-Corners tab, to 1.00 might fix it.
It should come set to 1.00 by default, but playing with this value (from 0.00 to quite higher) might help.
The new Panel-Colorizer applet allows including full transparency to both the Top Panel and Bottom Dock.
It can do a LOT more, you can customize many UI elements of your Plasma panels/docks.
If you want to use a different preset, do the following:
Configure Panel-Colorizer...