There is zero evidence of this that I have seen. Do you have any proof? The promotions have clearly said (both years) 11:59pm AEDT (well it was AEST last year) - basically Sydney time.
Unlike the case of eligible flights for earning (which GMT is irrelevant to, given it's based on local date/time of departure of the flight not GMT nor Zulu) the eligibility periods are very clear.
Also note the promotion disappeared off the QF.com main website within minutes of midnight passing
Re those with a ticketing date of 7 March - this is a curly one - it all depends on the PNR creation date. If it was set up on 06MAR but ticketing took some time that's where this was coming from.
Rather than waiting and hoping I'd *call* QF and verify what THEY think the booking date is for the purposes of the promo and, if need be, plead a delay in ticketing of a last minute booking and see if they might document the PNR or otherwise confirm that it would earn.
If one waits till June or something post flights it may be harder.
my 2 cents on this anyway.