It is the limbo waiting that is annoying, and costly for the passenger.
As mine was an award ticket I ended up cancelling my QF ticket (can do so free of charge at the moment) and paying for a fare on SQ, which is better value anyway @$584 return, Even though my QF was only one way, I’ll probably use the return sector and if I don’t still OK. SQ have been pretty reliably operating services to MEL for the last 22 months so barring an aircraft going out of service I expect they will operate their full achedule.