Because I was bored, a visual representation of this season's overnight 5-City Metro ratings, both against other shows in the 7:30pm timeslot and against previous seasons of this show. (The yellow line in the timeslot graph and the purple line in the TAR graph are this season; my software didn't want to cooperate and give them the same colour.)
Things worth noting:
(1) These figures exclude both streaming and regional figures so aren't quite accurate, but by all accounts both (especially the regional figures) aren't helping the show enough to change the results in any significant way.
(2) Because not every show airs for 90 minutes, I've used the figures for whichever shows were on Seven, Nine, and the ABC between 7:30pm and 8:00pm on each night, with the more accurate figures for the first two nights of the Australian Open taken from Nine's PR announcements (that none of the other networks who had access to the figures corrected, so which are presumably correct) rather than the averaged all-night figure used in the regular ratings reports for those nights.
(3) Yes, ratings for Holey Moley have dropped quite significantly. But more importantly, those people who ditched it haven't started watching this - this show didn't drop nearly as much the first couple of nights, but aside from this overtaking that from Episode 5 onwards, both shows' ratings have been rising and falling basically in parallel.
(4) This Sunday, where TAR won the timeslot by 34k, was the lowest-rated evening of commercial television of the year so far, even with this show's usual biggest audience (Melbourne) in lockdown.
(5) 7 out of 9 episodes so far are the lowest-rated episodes at the corresponding points in a TAR Australia season ever. Yes, it would be easy to blame that on the rise of streaming etc, except the Seven-era episodes generally aired in a later timeslot, with the premiere and both double episodes of Australia vs New Zealand in particular not finishing until after 11:00pm.
(6) Aside from the Australia vs New Zealand finale, which in addition to the later timeslot aired opposite a preview show for Australia's equivalent of the Superbowl, the four lowest-rated episodes in this show's history are all from this season.