someone else had this problem last week - it has something to
do with the qt5ct GTK theme, or some combinatino of themes

try deleting the qt5ct config

$ rm -rf ~/.config/qt5ct

if that does not help, try selecting a different GTK theme with
lxappearance; or selecting a different qt5ct theme using the
qt5ct program, something other than 'GTK2' like "fusion"

NOTE TO SELF: i think maybe 'qt5-styleplugins' needs to be rebuilt

Thank you very much!
Now I can start vlc, gqrx and calibre :3