It's a fair criticism - Australia's batting lineup is suspect. There have been a good number of batting collapses - both top and middle order - over the past years.
The opening situation is still unsettled with Khawaja recently turning 38 and not in terrific form, and no set partner for him. Labuschagne at 3 hasn't been in good touch (only 1 century since December 2022).
As for the middle order, Smith hasn't been quite his old, all-conquering self. Head has been a sole bright spot in an underperforming batting lineup for the past 2 years, and the less said about Marsh the better - he surely must be dropped for Sydney (and is frankly only in the team because there isn't anyone better to replace the injured Cameron Green who won't be back until after June's WTC final, if Australia qualify).
Our bowling stocks as usual seem fine, but whoever comes in next will have the burden of following up a generational attack that is unlikely to be repeated anytime soon. Not sure how much more Starc and Hazlewood have in the tank, but I would hope that Cummins could stick around for a 1-2 years after them to help blood in the next crop.
As
@Di Maria's angel said, there's no team at an absolutely elite level - on their day, any team can beat any other, Australia included.