>>6392730 (lb)
One of the first things I ever thought anon was that amongst the many possible meanings we were attach to Q was, in fact, Quarantine, i.e. the yellow Quarantine flag, where overtime the use shifted from a declaration of belief a ship was unsafe and in need of or under Quarantine, to a sign the ship was in fact CLEAN and in no need of Quarantine, i.e. here, we are clean (though you in port may not be lol)
each yellow vest is a little Q ship under Q in-keeping with the Kennedy-Flynn (Newport &c.) angle.
here's an interesting story