According to https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/4162#note_2739338 it was introduced as workaround for tearing issues. I do not experience any tearing without flushing on both nvidia and AMD GPU, so I suppose it's no longer needed. Slightly improve CPU usage according to my tests. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8348>