I did the usual thing of shooting with a phone which can do only 60fps (Samsung S7) under 50Hz fluorescent lighting.
Is there a plug-in in Vegas which can remove this? I can't find one and nothing turns up in google.
One interesting suggestion was to set video track opacity to 50%, create a copy of the track on another track, shift this second track along by 50ms (half of the flicker period) and render the lot :)