- Edited
Widevine have to provide libwidevinecdm.so in /usr/lib/qt6/plugins/ppapi/ so Falkon and other browsers to use drm content. The easier way, about me is https://dl.google.com/widevine-cdm/versions.txt provides versions they work with all chromium based browser, just for Qt is needed to have link in plugins.
https://dl.google.com/widevine-cdm/${version-from-link-above}-linux-x64.zip