Proper crew rest facilities involve a dedicated quiet area with horizontal bunks, I'm not sure that a couple of curtained off seat rows in the passenger cabin meet the requirements though they are better than nothing.
During the low point of COVID, Singapore Airlines was already planning for the recovery even though at the time there was no sign of it on the horizon. Staff were kept current and aircraft ticking over, a strategy was in place to meet demand once it bounced back. As a result they were first out of the starting gate and able to ramp up quickly as travel demand improved.
Even at the worst of they pandemic they were more use to Australians needing to get home than QF were.