The colored volume slider on the bottom right and the option "Always reset the audio start level to:" of media-video/vlc-2.1.0 could be set up to 200% in the past. Since the latest Qt update to 4.8.5 it can only be set up to 125% while the volume can still be set up to 200% with the keyboard shortcut Ctrl-Up. The OSD also still shows the volume up to 200%. So the GUI should also still be able to set the volume up to 200%. Reproducible: Always
Go into settings, switch "Show settings" to "all" then enter "maximum volume displayed" into the search bar. Now you can choose the qt main interface settings page where you can set the maximum volume back to 200%
Thanks! Worked.