What is with Qantas' horrible domestic reliability in May 2022?

Our QF flights to MEL LST were cancelled right as we were dropping our bags. It would seem the last second cancellation was deliberate to prevent us getting a refund and catching the Virgin flight about the same time. 5 hours wait in the domestic terminal with a toddler was not fun.
Everyone we told seemed to have a similar domestic horror story, no explanation or apology from the airline.
Is this just Qantas or is all domestic currently hit and miss?

Depends on loads. But its definitely not unheard of. Virgin also likes to cancel flights an hour or two out if one flight has really low loads and just shift people to the flight that is leaving later.