k.mp4
You need to copy and paste to your desktop the default folder in /usr/share/plasma/desktoptheme/default and alter the tasks.svgz in /usr/share/plasma/desktoptheme/default/widgets/tasks.svgz with inkscape and make everything transparent, or just use the file tasks.svgz
the altered default folder needs to be placed in the local folder to not mess up the original folder /usr/local/share/plasma/desktoptheme you need to create the desktoptheme if there's not one. I use kio-admin to make edits inside the root folder.
you need to copy and paste to your desktop the plasmoid org.kde.plasma.taskmanager in /usr/share/plasma/plasmoids/org.kde.plasma.taskmanager and then alter the qml file Task.qml in /usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml and replace the kirigami.icon with the code in task.qml.
then place the altered plasmoid org.kde.plasma.taskmanager in the local folder, /usr/local/share/plasma/plasmoids, you need to create the plasmoids folder if there's not one
log out and log in and it should be working
use the left right or top if you want your panel on the left right or top. if you have a light mode theme use the light mode